Wifi drops every 1-3 minutes after power outage

Thanks for the replies.

As I mentioned in my (addmittedly very long) post, I initially had the Centurylink Modem (ZyXEL C2100Z) between the fiber ONT and the Orbi. That worked great for maybe 6 months until I discovered (likely due to a firmware update) the ability to run the Orbi right into the fiber ONT without the C2100Z. That also has worked great ever since (~12 months).

Home is 2400 sq feet, 3 levels, stucco and plaster. I initially tried about a dozen physical arrangments for router and satellite, and settled on the router in the middle of the basement mounted on a bracket near the ceiling and the satellite on the next level about 4 feet off the ground and 20 feet over from the router. As mentioned, while troubleshooting, I also positioned all equipment in the same area in my basement. The behavior was the same regardless of either arrangement.

For channels, I've been using auto for 2.4 and 48 for 5g. Would a power outage somehow make that matter after a year and a half of excellent reliability?

I live in an urban area of mostly single family homes on city size (1/5 acre) lots, so I have dozens of wifi neighbors. I don't know about wifi broadcast devices. There isn't any sort of public wifi here, and most of my neighbors likely have a pretty basic setup compared to mine (ISP provided modem/router and a few client devices).

I did the factory reset from scratch, though I did save a config file before resetting. Haven't tried that since things weren't working well at the point when I saved it.