This looks like a warranty case. Please fill out this form and wait for a Teltonika sales manager to contact you via email. They will give some questions from Teltonika support engineers in order to determine whether the device is eligible for repair/replacement. I suggest taking a Troulbeshoot file (can be downloaded from the router's WebUI, System → Administration → Troubleshoot page) and photographing the WAN port (the lit up WAN LED without a cable connected should be visible in the picture).
Sending these files to the sales manager will help speed up the process. You can even send them a link to this forum thread.
You can read more about our warranty policy here.