Internet inturruptions

I live in north Phoenix, and have been having some internet issues for the past two months.  The interruptions last anywhere from 10 to 30 seconds, and the happens more frequently in the evenings. We are retired and at home during the day and probable have more internet activity during the day than in the evening.  At first I thought it might be my old router, an Orbi RBS50 that is about 5 years old.  So, I replaced it with a new TP Deco XE75 Pro, AXE5400 Tri-Band mesh Wi-Fi 6e system.  My modem is an Arris SB8200, and it is on Cox's approved list of modems for 1GB speeds which I currently subscribe to for internet speed.  The problem still exists.

Almost every time this happens, the modem status lights indicate that the modem is connected to the web.  But the router loses its internet connection.  It seems like a channel switching problem between the modem and the router.  But I am not sure if that is the whole story.  Some people having this same type of problem were told that the cause was due to a Cox update.