Enabling USB modem debug mode
For some reason, a USB modem connected directly to a router may sometimes be unable to establish a connection with the mobile operator's network.
By default, the router's system log displays brief connection information, which does not always allow us to determine the cause of a failure. Our support service may ask you to enable connection debugging (diagnostics) and send it to us so that we can find and resolve the issue.
Using the command-line interface (CLI) of the router, you can enable debug mode for a specific UDB modem interface.
5G/4G/3G modems connected to the router can operate in the following modes: RAS, CdcEthernet, NDIS and QMI. As a rule, when a modem is connected to the router, the settings automatically create the UsbModem0, CdcEthernet0 (for modems operating in these modes), UsbLte0 (for modems in NDIS mode) or Qmi0 (for modems in QMI mode).
To enable debugging, execute the following commands:
interface <interface_name> debug
system configuration save For example, to enable debugging on the USBModem0 interface, execute the following commands:
interface UsbModem0 debug system configuration save
The exact name of the modem interface used in the router can be found by entering the command:
show interface
Then press Space bar + Tab.
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Pay attention to the interface names. Be sure to consider the case of letters when using the interface name in commands. For example, the interface names UsbModem0, CdcEthernet0, UsbLte0 and Qmi0 contain both uppercase and lowercase letters.
After enabling or disabling the debug mode (diagnostics), the current connection is forcibly re-established.
If the purpose of enabling diagnostic mode is to determine the reasons for failure or disconnection from the mobile operator, you must wait for the failure or disconnection to occur.
If the problem is related to an error or a lack of a successful connection, then after enabling diagnostic mode, wait 2-3 minutes (during this time, the router will attempt several connections). Then, disable diagnostics.
To turn off modem debugging, execute the following commands:
no interface <interface_name> debug
system configuration save For example, to turn off debugging on the UsbModem0 interface, execute the following commands:
no interface UsbModem0 debug system configuration save
Now, save the router's system file, self-test.txt, and send it to our technical support service for diagnosis of the problem.