Internal Modem issues since Update.
Yesterday was everything fine…
I did the update in the evening…
Today every hour the modem is not working.
Sometimes everything fine after restarting, sometimes after looking minutes recovering.
Since switch back to 4G (12:00) no problems anymore.
Switched back to 5G, immediately Disconnected with:
Network O2 Germany - Reported to carrier —> No current issues known. 
Hello,
I updated the internal modem firmware from RG520NEBDCR03A04M4G_01.200.01.200 to RG520NEBDCR03A05M4G_A0.300.A0.300, but the issue persists. The modem repeatedly connects and disconnects after a few minutes.
Steps already performed (no improvement):
Factory reset
Installed the latest available router firmware
Switched SIM slots
Reconfigured APN settings
I also analyzed the system logs using Claude Code. The logs indicate a recurring loop related to the modem driver. Based on this, I suspect a modem firmware issue and believe an updated firmware version is required.
Update: Switching to 4G Band seems to work stable
Best regards,
Christian
same problem here!
seems that the modem agressively pushes 5G SA mode, which is not supported by carriers and then the modem is looping without connection.
Temporary fix with 4G only works for me, but is not the solution!
Greetings, @adam_muc ,
Welcome to Teltonika Community!
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 18440.
Please let me know once you filled out the form.
Thank you,
V.
I can also help with logs if required !
I hope you’re doing well.
At the moment, the issue is under investigation. I have already reached out to our R&D team and shared the details with them.
If any additional information is required from your side, such as logs or troubleshoot files, I will let you know.
I will keep you updated as soon as I receive further information from the R&D team.
In the meantime, we greatly appreciate your patience.
Best regards,
V.
Greetings, @omc69
Welcome to Teltonika Community!
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 18440-1.
Please let me know once you filled out the form.
Thank you,
V.
Greetings, @BLUEFIRE
Welcome to Teltonika Community!
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 18440-2.
Please let me know once you filled out the form.
Thank you,
V.
I have the same router, and I also have exactly the same issue after the modem update. Looking through the forum topics, this seems to be a common issue.
Greetings, @redspoons1 ,
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 18440-3.
Please let me know once you filled out the form.
Thank you,
V.
Thanks, I’ve filled it out
Greetings everyone,
@adam_muc , @omc69 , @BLUEFIRE , @redspoons1 ,
I have received an update from our R&D team. Please let me know if you still require assistance so we can arrange a remote session to help resolve the issue you are experiencing.
I look forward to your reply.
Best regards,
V.
Does the new firmware (07.22.1) that was released today solve the modem issue with the 5G connections? I don’t see a modem firmware update.
Hi…
This is only an update to the RutOS at the router… not the firmware of the modem lte, inside the router.
There is a message about modem firmware update… but no Release Notes, about it.
Your screengrab is a downgrade version from the problematic 05M4G modem firmware I think?
YES…
I just ignored the message about update lte modem and keep only updating RUTOS.
I tested the new device firmware, but it’s indeed still unstable in 5G mode. I hope that the new modem firmware will be released soon as well and we can enjoy proper 5G connectivity again.
Our C50 also indicates that the 5G connection is up, but the wifi clients don’t get internet access as long as 5G is enabled. When we switch off 5G (and only have a 4G mobile connection) all is fine though. No 5G speeds obviously.
