Hi. My suggestion would be not to switch Sonos from SonosNet to WiFi with a mesh WiFi.

Thank you so far,

I had to Google SonosNet and apparently it's about having one speaker connected by cable to the ethernet. 

I disconnected all speakers but left only one connected by cable, 

and now it is working,at least for the moment. 

​​​​​I have a Sonos Bridge as well but apparently it is old technology.

Regards,

Moonshine

You’ve assessed it all accurately. SonosNet is Sonos’ proprietary network protocol, designed to be activated when a single device (any except subwoofers or surround speakers) are connected to the root router. 

And yes, the BRIDGE was replaced by the newer BOOST back in 2013. It’s got more robust electronics in many ways, and can run either S1 or S2. The older BRIDGE is relegated to S1 only, and is commonly known at this age to have a dodgy power supply, which causes issues that are hard to diagnose properly. 

You can, I’m told, “trade in” the BRIDGE on the Sonos store website, to get a discount on the replacement BOOST, or you can, as you’ve discovered, just use one of the speakers, and just decommission the BRIDGE. 

BRIDGE or BOOST are not required, but they are handy in situations where it is impractical to wire another unit. They can also be used to support distant units. Place BRIDGE or BOOST about midway between a good coverage area and a poorly covered area. They can be wired or wireless.

Sorry, my initial response did lack detail.  I didn’t really grasp that you previously had all speakers wired.  Generally, mesh WiFi and Sonos in fully WiFi mode is not a happy combination.  As you say, wiring just a single Sonos device causes all traffic between Sonos speakers to be taken off your WiFi and onto SonosNet, which gives a much more reliable setup.

The wired connection allows devices connected over WiFi to talk to devices connected over SonosNet (in particular, controllers can talk to speakers.)