RUT956 no GSM connection

[mzalewski]

I have a Teltonika RUT956 router that worked correctly for about 2 years, but recently it stopped connecting to the GSM network despite detecting the SIM card and unlocking it by entering the SIM lock code. The log shows: “Mobile ESM reject cause: Unknown.” I tested it with 3 different SIM cards, all of which connect to the internet correctly in other devices. The latest firmware, RUT9M_R_00.07.19.1, is installed. I also tried flashing an older version, RUT9M_R_00.07.05 from 2023, because the modem was definitely working correctly at that time.
What could be causing the router to fail to connect to the GSM network, and is this something that can be fixed remotely or through software?

[Vilius]

Greetings, mzalewski,

Welcome to the Teltonika Community, and thank you for your message.

If you do not have any important configuration on the device, I recommend reinstalling the firmware using the bootloader menu. You can find the step-by-step instructions here:

RUT956 Device Recovery Options - Teltonika Networks Wiki

Additionally, could you please clarify the following:
• Are you using SIM cards from a single provider or multiple providers?
• Is the device operating in the same physical location as before?
• Are the mobile antennas properly attached and undamaged?

This information will help us narrow down the cause of the issue. If reinstalling the firmware through the bootloader menu does not improve the situation, please let me know and we will continue with the next troubleshooting steps.

I look forward to your reply.

Best wishes,
V.

[mzalewski]

Reinstalled with booloader menu and it’s still the same.

• multiple providers
• checked in different locations
• all GSM antennas are working; I checked other ones as well just to be sure.

[Vilius]

Hello,

Thank you for the follow-up, could you please confirm that the SIM card works in a different device e.g. Smarphone / tablet?

If it does, for troubleshooting purposes, we will require more sensitive information from your end, such as the troubleshoot file, which may contain passwords, public IP addresses, serial numbers, and such. To avoid leaking this information, we have sent you a form to fill out, which you will receive in your e-mail inbox that you have registered your account with in the forums. In the Ticket ID field of the form, please enter the ID of this thread, which is 16432.

Thank you,

V.

[mzalewski]

SIM card from my phone:

SIM card from RUT956 running fine in my phone.

[mzalewski]

That form doesn’t have file uploading feature.

[Vilius]

Once the form is filled out, I will send you an additional email with the instructions on how you can add a troubleshoot file.

Warm regards.

[Vilius]

Greetings,

Here’s a summary of our remote session:

During the session, I testing the connection using only the mobile interface, the internet connectivity was working properly. It appears that the issue was likely caused by an outdated firmware version. At this time, the issue has been resolved.

If you have any additional questions, please let me know.

Best regards,
V.