RAX80 device keeps going offline

I spent a ton of money on upgrading my home networking equipment for COVID, knowing that I had 2 full time students, 1 part time teacher, and 1 full time network professional using the network during work-from-home.

This device I purchased keeps going "dark". I am online and everything is fine, and then suddenly the device just stops responding. I cannot ping the router. The WiFi stops passing traffic. DNS resolution stops. Everything just goes dark. The only solution for this is to reboot the router.  I am rebooting the router several times a day, now. And this is HIGHLY DISRUPTIVE for online learning and work. 

I have checked the logs, but they seem to be wiped out on reboot so I can never tell if anything is logged that could point to a possible problem.

I have:

• Factory reset the router and reconfigured from scratch
• Replaced the network cabling
• Replaced the cable modem
• Replaced the power strip that is plugged into my UPS
• Pointed a fan directly at the unit in case it was overheating

My device was already replaced once by RMA and the replacement unit worked with the tolerable occassional lockup. But now they are happening multiple times per day. I seriously can't go on like this. 

I tried calling technical support, but "since the lights stay on" they refuse to consider it could be a hardware problem and won't replace it or even talk to me until I pay their technical support extortion fees.

I have a hardware warranty. Nothing I've configured should cause the unit to freeze like this. They refuse to replace it under warranty until I pay their support.