Hello,
Would it be possible to test the device with SIMs from other providers?
The logs are taken shortly after the device reboot, but there is an instance, where the modem disconnects and is not seen by the CPU, which would indicate modem hardware failure, especially considering that the modem is using the latest firmware.
You could also contact your ISP to enquire if they have the device's IMEI in their database.
Otherwise, if the same behavior repeats with other SIM cards, simply return the router.
Best regards,