Hello,
Could you try and update the firmware to the newest version, download link: https://wiki.teltonika-networks.com/view/RUTX11_Firmware_Downloads
If that does not help, you can try to restore device to factory settings, instructions can be found here: https://wiki.teltonika-networks.com/view/RUTX11_Device_Recovery_Options#Factory_reset
Could you download the troubleshoot file from WebUI System -> Administration -> Troubleshoot and send it to me via private message.
If your device still cannot detect the SIM card, could you verify, that the SIM card you are using is working. If the card is working, could you then download the troubleshoot file from WebUI System -> Administration -> Troubleshoot and send it to me via private message.
We will look over the file, and if we determine, that there in fact is no system errors, we suggest you to take the device to the place of purchase for warranty service.
Regards,
Paulius
