...

Introduction

Annotation

Modern trends of telecommunication development make operators find the most optimal technologies in order to satisfy rapidly growing needs of subscribers, at the same time maintaining consistency of business processes and flexibility in development, as well as reducing the costs of various services provision. Wireless technologies are gaining momentum and have evolved very quickly from unstable low-speed small radius communication networks to broadband networks comparable in speed to wired networks with high criteria for the quality of provided services.
WOP-2ac-LR5 is indended for organization of broadband networks in private housing. The device provides clients with wireless Internet access in the range of up to 3 km and Triple Play services. The device is a good choice for wireless network construction in any climatic conditions: in a wide operating temperature range and in high humidity. The device allows connecting different sectoral antennas.
This manual specifies intended purpose, main technical parameters, design, installation procedure and instructions for configuring, monitoring and updating of WOP-2ac-LR5 base station.

Explanation of the symbols used

...

Device description

Purpose

The base station WOP-2ac-LR5 (hereinafter 'the device') has been designed to provide subscribers with wireless Internet access in the range of up to 3 km and to organize wireless bridges (WDS).
The device provides access to modern interactive services: Internet, IPTV, VoIP.
The base station WOP-2ac-LR5 – an up-to-date flexible solution that provides extending coverage zone due to the power of its transmitter (up to 28 dBm) and the use of sectoral antennas. It is possible to deploy wireless IT infrastructure fast and easily by virtue of high-performance hardware, scalability and intuitive interface.
The PoE+ technology makes it possible to install the equipment anywhere, regardless of the power supply location, reduces total cost by discarding power cables and makes installation easier and faster.

Device specification

Interfaces:

• 1 Combo port 10/100/1000BASE-T (Ethernet)/100/1000Base-X (SFP);
• 2 SMA (female) connectors for external antennas. The choice of a model depends on the intended use of the access point: for wireless bridges, it is preferable to choose narrow-band antennas, and in the base station mode, sectoral antennas with a wider directional pattern are should be chosen.

...

Technical Features

Table 1 shows main specifications of the device.

...

² The number of channels and the value of the maximum output power will vary according to the rules of radio frequency regulation in your country.

Design

WOP-2ac-LR5 housed in a plastic case, industrial version. The size of the device: 80x232.5x47 mm. The appearance of WOP-2ac-LR5 is shown in the Fig. 2.

...

Light Indication

The appearance of WOP-2ac-LR5 indication panel is shown in the Fig. 4.

...

Reset to factory settings

You can reset the device configuration using the «F» button on the device.  When the device is loaded, press and hold the «F» button located on the bottom panel (approximately 10–15 seconds) until the «Power» indicator is flashing orange;
Device will be rebooted automatically. DHCP client will be launched by default. If the address is not received via DHCP, the device will have IP address — 192.168.1.10, subnet mask — 255.255.255.0; Username/Password to access via web interface: admin/password.

Delivery package

The basic supply package of WOP-2ac-LR5 includes:

• Base station WOP-2ac-LR5;
• Mounting kit;
• Patch cord RJ-45, 5e category, 1.5 m;
• Operating manual (supplied on a CD);
• Conformity certificate;
• Technical passport.

Installation order

This section defines safety rules, installation recommendations, setup procedure and the device starting procedure.

Якорь
instructions instructions

Safety Rules

1. Do not open the device case. There are no elements intended for user services inside.
2. Do not install the device during a thunderstorm. There is a risk of lightning strike.
3. Follow voltage, current and frequency requirements specified in the user manual.
4. Measuring devices and a computer must be grounded before being connected to the device. The electric potential difference between devices' housings should not exceed 1 V.
5. Make sure that all the cables are intact and that they are reliably attached to the connectors.
6. The specified standards and requirements for working at height must be met during the device installation on the high-rise constructions.
7. The device exploitation should be performed by specially trained engineering and technical personnel.
8. Connect only operational service equipment to the device.

Якорь
recommendations recommendations

Installation recommendations

1. Recommended location for device installation: communications mast/pole.
2. Before installing and enabling the device, check it for visible mechanical defects. In case of mechanical damage, you should stop the device installation, draw up a corresponding report and contact the supplier.
3. Install the device on communications mast or pole in the way that the Ethernet port is pointed down.
4. During the device installation, take into account the following rules to provide Wi-Fi coverage area with the best characteristics:
   1. Install the device in such a way that all subscriber stations that should be connected to this BS get into the antenna range;
   2. Do not install the device near (about 2 m) electrical and radio devices;
   3. It is not recommended to use radio phones and other devices, working on frequency of 5-6 GHz, within a range of wireless Wi-Fi network;
   4. Obstacles such as glass/metal constructions, brick/concrete walls, water cans and mirrors can significantly reduce Wi-Fi network range.
5. If several access points are placed on the same mast, it is recommended to spread them vertically by at least 2 meters.

Frequency bands and channels in the range of 5 GHz and 6 GHz for Wi-Fi

Data transmission in the 5-6 GHz band is used for IEEE 802.11a/n/ac standards. WOP-2ac-LR5 supports frequency channels in the range of 5-6 GHz with the bandwidth of 5, 10, 20, 40 and 80 MHz.
To calculate the Wi-Fi channel central frequency, MHz, use the equation:
f=5000+(5*N), where N – Wi-Fi channel number.

WOP-2ac-LR5 mounting

1. Attach the bracket to the device with the screws provided, as shown in the figure below.

   

2. Install the device on communications mast/pole with Ethernet port down as it is shown in the figure below. Attach the device using clamps supplied in the device package. Follow the safety rules and recommendations given in Safety rules and Installation recommendations.

   
   

   

   
   

3. Remove the cover that closes the Ethernet port on the bottom panel of the device. Ground the device using a grounding connector (for H/W version: 1v5 and higher), then connect the Ethernet cable to the PoE port. When building a network over fiber, install the transceiver and make the connection.
   

   

4. Close the bottom cover.
5. Connect the antenna to the device using the cable assemblies.
6. Adjust the position of the antenna so that subscriber devices fall into the coverage area of the installed antenna.
7. Connect the Ethernet cable coming from WOP-2ac-LR5 to the PoE port or the injector or switch (IEEE 802.3at-2009).
8. If you use a PoE injector, connect it to 220 V power supply network using the cable.
9. Adjust the antenna more precisely using light indicators on the device.

Managing the device through WEB interface

Getting started

To start, you need to connect the device through a browser:

...

5. If necessary, you can switch the display language. Russin and English languages are available for WOP-2ac-LR5.

Applying configuration and discarding changes

1. Applying configuration

...

The button for discarding changes appears as follows: .

Main Elements of the web Interface

Navigation elements of the web interface are shown in the figure below.

...

1. Menu tabs categorize the submenu tabs: Monitoring, Radio, VAP, WDS, Network settings, System.
2. Interface language selection and Logout button designed to to end a session in the web interface under a given user.
3. Submenu tabs allows controlling the settings field.
4. Device configuration field displays data and configuration.
5. Information field displays current firmware version.

Scroll Pagebreak

The «Monitoring» menu

The 'Monitoring' menu displays the current system status.

The 'Wi-Fi Clients' submenu

The 'Wi-Fi clients' submenu displays information about the status of connected Wi-Fi clients.

...

• № – number of the connected device in the list;
• Hostname – network name of the device;
• IP address – IP address of the connected device;
• MAC address – MAC address of the connected device;
• Interface – WOP-2ac-LR5 interface for interaction with the connected device;
• Link Capacity – parameter that reflects the efficiency of modulation on the transmission used by an access point. It is calculated based on the number of packets transmitted to the client on each modulation, and the reduction factors. The maximum value is 100% (means that all packets are transmitted to the client at maximum modulation for the maximum nss type supported by the client). The minimum value is 2% (in the case when the packets are transmitted on the modulation nss1mcs0 for a client with MIMO 3x3 support). The parameter value is calculated for the last 10 s;
• Link Quality – parameter that displays the status of the link to the client, calculated based on the number of retransmit packets sent to the client. The maximum value is 100% (all transmitted packets were sent on the first attempt), the minimum value is 0% (no packets were successfully sent to the client). The parameter value is calculated for the last 10 s;
• Link Quality Common – parameter that displays the status of the link to the client, calculated based on the number of retransmitted packets sent to the client. The maximum value is 100% (all transmitted packets were sent on the first attempt), the minimum value is 0% (no packets were successfully sent to the client). The parameter value is calculated for all the time the client is connected;
• RSSI – received signal level, dBm;
• SNR – signal/noise ratio, dB;
• TxRate – channel data rate of transmission, Mbps;
• RxRate – channel data rate of receiving, Mbps;
• TxBW – transmission bandwidth, MHz;
• RxBW – receive bandwidth, MHz;
• Uptime – Wi-Fi client connection time;
• Total TX / RX, bytes – the number of bytes sent/received on the connected device;
• Total TX / RX, packets – the number of packets sent/received on the connected device;
• Data TX / RX, bytes – the number of data bytes sent/received on the connected device;
• Data TX / RX, packets – the number of data packets sent/received on the connected device;
• Fails, packets – the number of packets sent with errors to the connected device;
• TX Period Retry, packets – the number of retransmissions to the connected device in the last 10 s;
• TX Retry Count, packets – the number of retransmissions to the connected device during all the time of connection;
• Actual TX / RX Rate, Kbps – the current traffic transmission rate.

Scroll Pagebreak

The 'WDS' submenu

The 'WDS' submenu displays information about the status of connected via WDS WOP-2ac-LR5.

...

• № – number of the connected device in the list;
• Hostname – network name of the device;
• IP address – IP address of the connected device;
• MAC address – MAC address of the connected device;
• Interface – WOP-2ac-LR5 interface for interaction with the connected device;
• Link Capacity – parameter that reflects the efficiency of modulation on the transmission used by an access point. It is calculated based on the number of packets transmitted to the client on each modulation, and the reduction factors. The maximum value is 100% (means that all packets are transmitted to the client at maximum modulation for the maximum nss type supported by the client). The minimum value is 2% (in the case when the packets are transmitted on the modulation nss1mcs0 for a client with MIMO 3x3 support). The parameter value is calculated for the last 10 s;
• Link Quality – parameter that displays the status of the link to the client, calculated based on the number of retransmit packets sent to the client. The maximum value is 100% (all transmitted packets were sent on the first attempt), the minimum value is 0% (no packets were successfully sent to the client). The parameter value is calculated for the last 10 s;
• Link Quality Common – parameter that displays the status of the link to the client, calculated based on the number of retransmitted packets sent to the client. The maximum value is 100% (all transmitted packets were sent on the first attempt), the minimum value is 0% (no packets were successfully sent to the client). The parameter value is calculated for all the time the client is connected;
• RSSI – received signal level, dBm;
• SNR – signal/noise ratio, dB;
• TxRate – channel data rate of transmission, Mbps;
• RxRate – channel data rate of receiving, Mbps;
• TxBW – transmission bandwidth, MHz;
• RxBW – receive bandwidth, MHz;
• Uptime – connection uptime.
• Total TX / RX, bytes – the number of bytes sent/received on the connected device;
• Total TX / RX, packets – the number of packets sent/received on the connected device;
• Data TX / RX, bytes – the number of data bytes sent/received on the connected device;
• Data TX / RX, packets – the number of data packets sent/received on the connected device;
• Fails, packets – the number of packets sent with errors to the connected device;
• TX Period Retry, packets – the number of retransmissions to the connected device in the last 10 s.
• TX Retry Count, packets – the number of retransmissions to the connected device during the entire connection.
• Actual TX / RX Rate, Kbps – the current traffic transmission rate.

The 'Traffic Statistics' submenu

The 'Traffic Statistics' section displays the diagrams of the transmitted/received traffic speed for the last minute, as well as statistics on the amount of transmitted/received traffic since the access point was turned on.

...

• Interface – name of the interface;
• Total packets – number of successfully received packets;
• Total bytes – number of successfully received bytes;
• Total drop – number of rejected packets;
• Errors – number of errors.

The 'Scan Environment' submenu

In the 'Scan Environment' submenu, the radio environment scanning and neighboring access points detection are carried out.

...

The 'Events' submenu

In this section, you can view a list of real-time informational messages which contains the following information:

...

The 'Network Information' submenu

In the 'Network Information' submenu common network settings of the device can be viewed.

...

• Interface – name of the bridge interface;
• Destination– IP address of destination host or subnet that the route is established to;
• Gateway – IP address of a gateway used for the access to the Destination;
• Netmask – subnet mask;
• Flags – certain route characteristics. The following flag values exist:
  • U – means that the route is created and passable;
  • H – identifies the route to the specific host;
  • G – means that the route lies through the external gateway. System network interface provides routes to networks with direct connection. All other routes lie through external gateways. G flag is used for all routes except for the routes to the direct connection networks.
  • R – indicates that the route was most likely created by a dynamic routing protocol running on the local system using the reinstate parameter;
  • D – indicates that the route was added as a result of receiving an ICMP Redirect Message. When the system learns the route from the ICMP Redirect message, the route will be added into the routing table in order to prevent redirection of the following packets intended for the same destination.
  • M – means that the route was modified – likely by a dynamic routing protocol running on a local system with the 'mod' parameter applied;
  • A – points to a buffered route, which an entry in the ARP table corresponds to.
  • C – means that the core routing buffer is the route source;
  • L – indicates that one of the addresses of the computer is the route destination. Such "local routes" exist in the routing buffer only.
  • B – indicates that a broadcasting address is the route destination. Such "broadcast routes" exist in the routing buffer only.
  • I – indicates that the route is connected to a ring (loopback) interface for a purpose other than to access the ring network. Such 'internal routes' exist in the routing buffer only.
  • ! – means that datagrams sent to the address will be rejected by the system.

    Scroll Pagebreak

The 'Device Information' submenu

The 'Device Information' submenu displays main WOP-2ac-LR5 parameters.

...

• Product – device model name;
• Hardware Version – device hardware version;
• Factory MAC Address – device WAN interface MAC address set by the manufacturer;
• Serial Number – device serial number set by manufacturer;
• Firmware Version – device firmware version;
• Backup Version – previously installed firmware version;
• Boot Version – device bootloader firmware version;
• System Time – current time and date set in system;
• Uptime – the time since the last time the device was turned on or restarted.

  Scroll Pagebreak

The 'Radio' menu

In the 'Radio' menu the wireless interface can be configured.

The 'Radio' submenu

In the 'Radio' submenu, the device radio interface's parameters are configured.

...

• OBSS Coexistence – automatic channel bandwidth reduction mode when the environment is loaded. When the flag is set, the mode is enabled;
• DFS Support – dynamic frequency selection mechanism. The mechanism requires wireless devices scan environment and avoid using channels that coincide with channels on which radiolocation systems operate at 5 GHz:
  • Disabled – the mechanism is disabled. DFS channels are not available for selection;
  • Enabled – the mechanism is enabled;
  • Forced – the mechanism is disabled. DFS channels are available for selection.
• Short Guard interval – support for Short Guard interval. Access point transmits data using 400 ns Guard interval (instead of 800 ns) to clients that also support Short GI;
• STBC – Space-Time Block Coding method dedicated to improve data transmission reliability. The field is available only if the selected mode of radio interface operation includes 802.11n. When checked, the device transmits one data flow through several antennas. When unchecked, the device does not transmit one data flow through several antennas.
• Beacon Interval, ms – beacon frames transmission period. The frames are sent to detect access points. The parameter takes values from 20 to 2000 ms, by default – 100 ms;
• Fragmentation Threshold – frame fragmentation threshold, bytes. The parameter takes values 256-2346, by default – 2346;
• RTS Threshold – specifies the number of bytes after which the transmission request will be sent (Request to Send). Decreasing the parameter's value might improve access point operation when there are a lot of clients connected. However, it will reduce general bandwidth of a wireless network. The parameter takes values from 0 to 2347, by default – 2347;
• Aggregation – enable support for AMPDU/AMSDU;
• Short Preamble – use of the packet short preamble;
• Broadcast/Multicast Rate Limiting, p/s – when the flag is set, transmission of broadcast/multicast traffic over the wireless network is restricted. Specify the limit for broadcast traffic in the opened window (packets per second).

  Scroll Pagebreak

The 'QoS' submenu

In the 'QoS' submenu, Quality of Service functions are configured.

...

To apply a new configuration and save settings to non-volatile memory, click «Apply». Click «Cancel» to discard the changes.

The 'VAP' menu

In the 'VAP' menu, virtual Wi-Fi access points (VAP) are configured.

The 'Summary' submenu

The 'Summary' submenu displays the settings of all VAPs. You can see the settings of each virtual access point in sections VAP0..3.

...

To apply a new configuration and save setting to non-volatile memory, press «Apply». Press «Cancel» to discard the changes.

The 'VAP' submenu

Common settings

• Enabled – when checked, the virtual access point is enabled, otherwise it is disabled;
• VLAN ID – number of VLAN from which the tag will be removed when transmitting Wi-Fi traffic to clients connected to this VAP. When traffic flows in the opposite direction, untagged traffic frоm clients will be tagged with VLAN ID (when VLAN Trunk mode is disabled);
• SSID – virtual wireless network name;
• Broadcast SSID – when checked, SSID broadcasting is on, otherwise it is disabled;
• VLAN Trunk – when the flag is set, tagged traffic is transmitted to the subscriber;
• General Mode –  when the flag is set, transmission of untagged traffic jointly with tagged traffic is allowed (available when Trunk VLAN mode is enabled);
• General VLAN ID –  a tag will be removed from the specified VLAN ID and the traffic of this VLAN will pass to the client without a tag. When traffic passes in the opposite direction, untagged traffic will be tagged with General VLAN ID;
• Station Isolation – when checked, traffic isolation between clients on the same VAP is enabled.
• Maximum Stations – the maximum number of clients connected to the virtual network;
• Security – wireless access security mode:
  • Off – do not use encryption for data transfer. The access point is available for any subscriber to connect;
  • WPA, WPA2, WPA/WPA2 – encryption methods for which the following setting will be available:
    • WPA Key – key/password required to connect to the virtual access point. The length of the key is from 8 to 63 characters;
  • WPA-Enterprise, WPA2-Enterprise, WPA/WPA2-Enterprise – wireless channel encryption mode, according to which the client is authorized on the centralized RADIUS server. To configure this security mode, you must specify the parameters of the RADIUS server. You also need to specify a key for the RADIUS server. If you select one of the methods, the following setting will be available:
    • Domain – user domain;
    • IP Address of RADIUS Server – RADIUS server address;
    • Port of RADIUS Server – port of the RADIUS server used for authentication and authorization;
    • Password of RADIUS Server – password for the RADIUS server used for authentication and authorization;
    • Use Accounting through RADIUS – when checked, 'Accounting' messages will be sent to the RADIUS server;
    • Use Other Settings For Accounting
      • IP Address of RADIUS Server for Accounting – address of the RADIUS server used for accounting;
      • Port of RADIUS Server for Accounting – port that will be used for accounting on the RADIUS server;
      • Password of RADIUS Server for Accounting– password for the RADIUS server used for accounting;
      • Use Periodic Accounting – enable periodic sending of 'Accounting' messages to the RADIUS server. You can set the interval for sending messages in the 'Accounting Interval' field.

...

To apply a new configuration and save settings to non-volatile memory, click «Apply». Click «Cancel» to discard the changes.

The 'WDS' menu

In the 'WDS'menu, wireless bridges are configured for WOP-2ac-LR5.

The 'WDS' submenu

• Enabled – when the flag is set, the wireless bridge mode is enabled; otherwise, it is disabled;
• Security – wireless network access security mode:
  • Off – do not use encryption for data transfer;
  • WPA2 – encryption method for which the following setting is available:
    • WPA Key – key/password required to connect to the virtual access point. The key length is from 8 to 63 characters.
• Link X (where X=0..7) – enable wireless bridge link;
• MAC – MAC address of the opposite device to which the wireless bridge is configured;
• Fixed Transmit Rate – fixed wireless data transmission rate which defined by IEEE 802.11a/n/ac standards and selected individually for each link.

The 'Network Settings' menu

The 'System Configuration' submenu

• Hostname – nertwork name of the device specified by a string from 1 to 63 characters; latin uppercase and lowercase letters, numbers, hyphen '-' (hyphen can not be the last character in the name);
• Management VLAN:
  • Disabled – Management VLAN is not used;
  • Terminating – the mode where the management VLAN is terminated at the access point; in this case, clients connected via the radio interface do not have access to this VLAN;
  • Forwarding – the mode where the management VLAN is also transmitted to the radio interface (with the appropriate VAP configuration).
• VLAN ID – the VLAN ID used to access the device, takes values 1-4094;
• Protocol – protocol that will be used to connect the device to service provider network via Ethernet interface:
  • DHCP– operation mode where IP address, subnet mask, DNS server address, defualt gateway and other parameters required for operation are obtained from DHCP server automatically;
  • Static – operation mode where IP address and all the necessary parameters for WAN interface are assigned statically. If «Static» is selected, the following parameters will be available to configure:
    • Static IP – device WAN interface IP address in the provider network;
    • Netmask – external subnet mask;
    • Gateway – address to which a packet is sent, if the route has not been found in a routing table;
  • Primary DNS server, Secondary DNS server – IP addresses of DNS servers. If DNS servers' addresses are not allocated automatically via DHCP, set them manually.

To apply a new configuration and save settings to non-volatile memory, click «Apply». Click «Cancel» to discard the changes.

The 'Access' submenu

In the 'Access' submenu, access to the device via the web interface, Telnet, SSH, NETCONF and SNMP is configured.

...

where eltexLtd – 1.3.6.1.4.1.35265 is Eltex Enterprise identifier.
To apply a new configuration and save settings to non-volatile memory, click «Apply». Click «Cancel» to discard the changes.

The 'System' menu

In 'System' submenu, configuration of system, time, access to the device via different protocols as well as password change and software update can be performed.

The 'Device Firmware Upgrade' submenu

The 'Device Firmware Upgrade' submenu is used to update the device firmware.

...

The 'Configuration' submenu

In the 'Configuration' submenu current configuration is saved and updated.

...

To reset all the settings to default values, click «Reset» button. If the checkbox 'Save access setting' is selected, configuration parameters that are responsible for access to the device (IP address settings, Telnet/SSH/SNMP/Netconf/WEB access settings) will be saved.

The 'Reboot' submenu

To reboot the device, click the 'Reboot' button. The device reboot process takes about 1 minute.

The 'Password' submenu

When logging in via WEB interface, administrator (default password: password) has the full access to the device: read/write access to any settings, full device status monitoring.
To change a password, enter a new one first in the 'Password' field, and then in the 'Confirm Password' field. Click the 'Apply' button to save a new password.

The 'Log' submenu

The 'Log' submenu is intended to configure the output of different system debugging messages in order to detect causes of the device operation problems.

• Mode – Syslog agent operation mode:
  • Local File – log information is stored in a local file and is available in the device’s web interface in the 'Monitoring/Events' tab;
  • Server and File – log information is sent to a remote Syslog server and stored in a local file.
• Syslog Server Address – IP address or domain name of the Syslog server;
• Syslog Server Port – port for incoming Syslog server messages (default: 514, valid values: from 1 to 65535);
• File Size, KiB – maximum size of the log file (valid values: 1-1000 kB).

The 'Date and Time' submenu

In the 'Date and Time' submenu, you can set the time manually or using the time synchronization protocol (NTP).
Manual:

...

To apply a new configuration and save settings to the non-volatile memory, click the 'Apply' button. To discard changes, click the 'Cancel' button.

Spectrum Analyzer

To use the embedded spectrum analyzer on the WOP-2ac-LR5, you need to login to the device via telnet or ssh.

...

WOP-2ac-LR5(root):/# monitoring spectrum-analyzer
Channel| CCA
     36| 4%
     37| 3%
     38| 1%
     39| 5%
     40| 3%
     41| 5%
     42| 1%
     43| 6%
     44| 4%
     45| 3%
     46| 1%
     47| 4%
     48| 4%
     49| 4%
     ...

System recovering after firmware update failure

If a failure (e.g. due to power cutoff) occured during the firmware update (via the web interface or via DHCP-based automatic update mechanism), and the device does not operate (the «Power» indicator is solid red), use the following algorithm to recover the device:

• Unzip the archive with the firmware file.
• Connect a PC to the device port. Specify the following subnet mask on the network interface: 192.168.1.0/24.
• Run the TFTP client on the PC (for Windows, it is recommended to use the Tftpd32), specify 192.168.1.6 as the remote host address and select the linux.bin file from the unzipped firmware archive for transferring.
• Run the command to send a file to the remote host (the Put command). The process of file transmission will be launched.
• If transmission process has been started, please, wait for its finishing. The device will write the firmware to its memory and launch the system automatically. Writing takes approximately 8 minutes. If the process is completed successfully, the "Power" indicator will be green or orange. The configuration that was used before the failure will be stored on the device. If you can not connect to the device, reset it to factory settings.
• If the process has not started, make sure that PC network settings are correct and try again. If it does not work, send the device to maintainance service or connect to the device via the COM port using a special adapter (if available) and perform recovery.

The list of changes

...