RUT240 looses connection when opening WebUI

I have a RUT240 connected to a mobile network with a private APN. The system itself is working, there more routers set up in the same way. Also this is no problem with the signal strength.
When i try to log in to the WebUI (the log in screen is working) or try to access devices in the network, the router looses the connection for a few seconds multiple times. On the other hand connecting via ssh is possible.
What could cause such behaviour?

Hello,

You can try connecting to the device via SSH and execute the ‘logread -f’ command to see logs in real-time. Then, try connecting to the WebUI of the device and see if there are any relevant logs.

Does the issue persist if you do a factory reset? You can download a backup file, restore the device to factory settings to see if the issue is still there, and then upload the backup to restore all the configurations. If the issue reappears, it may be related to configurations.

Also, have you tried flashing the firmware via bootloader as described here?

Kind Regards,