Sounds like communications issues, have you tried the otter two available WiFi channels?
Any electronic devices within 3 feet of any of the Sonos, not just ones with radios? Try unplugging them for a quick test to see if they are causing the issues.
Stanley,
Thank you for your help. Your suggestion had me looking at my network for the issue. I was shocked to see the Era 300 were not using Sonos Net. I think this is a mistake by Sonos as Sonos Net works wonderfully. But for whatever reason Sonos went with wifi 6 over Sonos Net on the ERA series.
The ERA 300 were bouncing back and forth between my 2.4ghz and 5ghz networks. This hadn’t been an issue before for me with a house full of Sonos gear as everything used Sonos Net.
I renamed my 2.4ghz network and removed it from the Sonos App, this took several tries at it kept popping up even after having been deleted. Not sure why that happened.
I also added a gen 3 sub to the Era 300 pair. Now those three speakers are running well over my 5ghz network. I can confirm that this set up sounds excellent. I also tried the Era 300 as rear surrounds and I feel they are wasted in that configuration, but I know that isn’t a popular opinion.
Thank you again for your time