Hello,
To better understand the issue, I'll ask you to replicate the issue and navigate to System → Administration → Troubleshoot. Generate a troubleshoot file and attach it to the original post. It will only be visible to Teltonika moderators.
Additionally, if you don't have a lot of configuration on the RUTX50, there is the option to re-flash the device using the bootloader method, which is described here. I'd recommend trying this before generating a troubleshoot file.
Since the data state is connected, this is most likely not the cause, but I will still ask you to doublecheck if the correct APN is used on the SIM card.
Also, if you are only using WiFi devices, try the 5GHz channel.
Best regards,
DaumantasG