Does the SIM work in a mobile device, is it not bound to a single device?
From the logs it is seen that the LTE signal indicator values are rather poor.
You can try placing the router in a different location.
Another thing you can change is the LTE band the router connects to. Currently, it is connected to band 28. By following the instructions in this video, test the following ones: 1, 3, 7, 8. You can see signal parameters in the WebUI Status -> Network -> Mobile section. For reference values, check this page.