Thank you for contacting Teltonika Networks crowd support community.
Apologies for the technical issue you are having on your end.
Note: This solution will work when you have connected RUT955 to another source of internet except mobile, i.e., Wired WAN or Wireless WAN.
Access your device via SSH and execute the following commands:
opkg install modem_updater
opkg install sshfs
The last command will list available firmware versions. Next modify the following command:
modem_updater -i <ID> -v <VERSION>
<ID> - should be 1-1.4, however, in case of an error you should be shown a correct ID.
<VERSION> - enter the latest firmware version from the list of the previously executed command.
The modem should automatically restart itself.