Created the post to bring the fix to the top level. tl;dr if you turn off "Automatically adjust for daylight savings time" (under Advanced -> Administration -> NTP Settings) and put in a server under "Set your preferred NTP server" (I use "pool.ntp.org"), then the internet drops will be fixed. I found the path to the solution buried in comments on other threads. I did not need to do any other changes to firmware version (2.7.2.104) or Circle settings.
This week was our spring break. While we were travelling, I started getting all sorts of notifications that my home security cameras were losing their connection. I thought it was perhaps the camera service failing; but when we got home, it became clear it was either the router or the modem. I stuck another router between the modem and the Orbi, and that consistently had internet even though the Orbi did not. I tried several reboots, disabling Circle, nothing was working. Googling got me to an answer to disable DST and put in your own NTP server. I already was using pool.ntp.org, so, all I had to change was to disable DST, and reboot, and it's been solid since with Circle enabled. And, of course, this week was the week when DST went into effect, so, it makes sense that I'd start having issues this week.
I hope that helps people, it would be great if a future firmware udpate resolved the issue, but, I was contemplating getting a new router and didn't relish that, and now I don't have to, so major win!
