Hi @Tiger4969
Welcome to the Sonos Community!
Sorry to hear about the issues you had, and I am glad to hear that you have resolved them already!
As for insights, speakers being slow to start or cutting out once they have is typically due to interference on WiFi. Why this would happen, I can only guess (certainly without seeing any diagnostics, it will be a guess), but if it seems switching to SonosNet solved the issue, then I think interference at the router is the most likely cause, possibly itself caused by a device situated close to the router itself. Certainly, if the ethernet-wired speaker is a distance away from the router, that would support this idea.
Likely, the wired speaker is broadcasting on a channel different than the router is using and is therefore not being interfered with as much. It all depends on the placement of various devices and the channels in use by them.
You may find our Reduce wireless interference help page of some use.
There is no correct answer when it comes to SonosNet and WiFi - use whichever produces the best results. You may also find my article of use:
I hope this helps.
Thanks for the details. The ethernet wired speaker is actually my sonos amp and is about 35-40’ from the Gateway EERO, am using Cat 6 ethernet everywhere. I’ll check out that article, thanks.