Sure sounds like a potential case to read the wifi interference FAQ. And be aware that a lot of wifi interference isn’t from inside your network, but from outside. I’ve personally had issues with both a bad microwave, as well as a new neighbor deploying a router that stomped on the channel I was using for SonosNet. 

If I were to guess, there’s just enough interference to bother you when you’re attempting to get all three rooms to play at the same time, but not enough to impact when playing only 2 rooms at a time. So it’s borderline, which will make it somewhat harder to chase down. 

Thanks for Answer…

I tried every channel and I check with my WIFI sofware on my laptop and every channel on my 2.4 is very clean...

@Gravel,

See which (2.4Ghz/5Ghz) WiFi band your ‘Move’ is using in the Sonos App network settings and just see what happens when you switch it to the other WiFi band. Also set your routers 2.4Ghz band to use a channel-width of 20Mhz only and start the music playback using your wired Sonos Arc as the group co-ordinator and see if that resolves your issue.

Most WiFi monitors only check for other WiFi signals, they do not show other things using or just polluting the WiFi channels.

Since you have the Arc wired you might get something from the Network Matrix.

Use your IP here, not the 0.0.0.0:  http://0.0.0.0:1400/support/review