Help!! My modem randomly restarts

I have been on xFinity home internet for 3 weeks now. I started with the Motorola SB6121. It was randomly restarting. When I called xFinity to get help, tech support told me that the issue is likely my modem because it is "end of life". Given that it was an intermittent issue, find it unlikely that an electronic device could work for a few days straight but then on many days would reboot multiple time. I begrudgingly bout a new modem - the Arris SBV2402. Well, this Arris modem is exhibiting the same issue (random reboots). 2 modems with the same intermittent problem and xFinity tech support tells me that everything is perfect on their end and I need to get help from the modem manufacturer.

This random modem rebooting issue appears to be somewhat common on the forum. Has anyone found the root cause? I am beyond frustrated.