Update for those who are following. After extensive research on this here was my solution. If this is not solid I will report back.
First I acknowledge @AjTrek1 for his link on mesh for Sonos. To anyone from Sonos watching. Take the reference out of a footnote and really it’s 2026 almost, put a whole page on this.
Second for me I switched my Netgear extender from having the same SSID’s that I set up to using their One Wifi. This has provided a more stable extender and quicker switching. I have one of four rooms on this extender.
The big difference though. Instead of using the Powerline for the extender I put the Arc Ultra on it. In case you aren’t aware, the Ultra doesn’t support the Sonos Zip network. The rest of my products are on it including the one off the extender. I was surprised how easy it was to set up. I got the TP Link AV2000. What I am seeing is there is no more struggling on my Mac to see the system, and no more complaints about the firewall or updating. I think this will solve my particular problem which arises because of my layout where the Ultra would switch from the router to the extender and then the problems would arise. This seems to have solved this.
UPDATE - literally - just did an Ultra update from my Mac. Use to fail if on the extender. When the update started the Ultra and the room on the extender were grouped. With this wired set up it updated the Ultra, finished and regrouped them. no issues.
If it doesn’t I will report back. Thanks to everyone for helping expand my understanding of everything.
Postscript for those that are from Network experts like me. What I learned is the Extender in Extender Mode switches quicker than in Access Point mode, even with the same SSIDs set up in AP mode. Since we have things besides Sonos that wasn’t great. My set up is a router and extender, not a current system advertised as MESH. Mine was sort of the latest before the current mesh systems. I am glad that Sonos is working better with the current mesh systems.