Based on the logs, it appears that the device is attempting to use either an empty APN or 'internet' as the APN, which is resulting in failure. Could you please try to manually configure an APN in Network -> Interfaces -> Edit mob1s1a1 interface? There, you can disable auto-APN and enter a custom APN.
You can try inserting the SIM card into your phone and checking the APN it uses. Then, try configuring the same APN on the router.
Additionally, have you recently updated the firmware? If so, I recommend trying to restore the device to its factory defaults. You can do this in System -> Backup. Restoring to factory defaults can help to resolve any migration issues that may have occurred during the firmware update.
Let me know about the results.