Are you selecting multiple speakers to play to by Airplay, or are you grouping in the Sonos app then Airplaying to one of the group?  I would expect the latter to be more stable.

I am selecting multiple speakers in airplay. I don’t see a way to group speakers in sonos and have that reflected in airplay. Please enlighten me!

Just Airplay to one of the speakers then group other speakers to it in the Sonos app.  

Got it, thanks. It’s a 2-step process which is not ideal, but worth it if its reliable.

Is there a google assistant voice command (or better yet scene?)  to do the grouping of the other speakers to the airplay-ing speaker? 

I don't use GA but I think its very unlikely.

If there's a grouping you use often then you could set that up as a user-defined group. That's only going to save you a tap or two though.

thanks. I already have a user-group defined inside sonos.

Is the instability of sonos speakers grouped by airplay a known problem?

The problem is Airplay. You haven't been using Sonos groups up to now.

We I tried you suggestion, John B, and a few minutes in it stopped playing. YouTube music was in play mode (displaying a pause symbol) but the song position marker wasn’t moving. Airplay still thought it was connected to the one speaker I connected to airplay in the beginning. When I reverted back it iPhone on the airplay menu it started playing again.

Any ideas?

That certainly suggests some sort of wifi interference issue, as Sonos has no control over any application you are using AirPlay 2 on, all it functions as is a receiver of data.
 

It might be worth checking your network, as my guess would be that your phone is dropping the connection, which would be why the song position marker in the YouTube Music wasn’t moving. Any temporary music you would be hearing would be the buffer running out, and not actually music being transferred at the time. 

I can stream 4k video without a problem…

Having said that, is there a way to monitor my wifi network for momentary drop outs? 

The fact that you can stream 4K video is irrelevant.  That only involves one device, whereas with Sonos you have several devices that need to stay in constant touch.  That is actually more demanding on a network.  Or, at least, makes very different demands.

You could try any and all of the following when grouping in Sonos:

1. Change the speaker you start the group from.  This should ideally be the one with the strongest signal. 
2. As an experiment, you could try connecting one of your speakers by Ethernet to your router, and start the group from there
3. Submit a system diagnostic when a dropout has occurred and then call Sonos Support with the confirmation number

Incidentally, do you have any access points, extenders etc on your network?

How many rooms are you grouping?

Do you get the same problem with internet radio?

Thanks again, John.

1. Change speaker… I can try that!
2. Connect to router … 1 speaker is next to a mesh router.  So I can try that, but I doubt it is having trouble talking to the router
3. Submit diagnostic - will do!

I have a eero mesh router with routers in relative close proximity including 1 eero extender.

I am grouping 4 or 5 rooms.

I don’t use internet radio (can’t tolerate commercials!) 

Thanks!
 

‘Next to’ is almost as bad as ‘too far away’. It should be around 3 feet / 1 meter  apart for a good radio signal.

The issue may well relate to running Sonos in fully WiFi mode on a mesh system. 

Wire a speaker to the main Eero device. Wait a couple of minutes and check in About My System that all Sonos devices (except Move and Roam) have WM=0 not WM=1. If any have WM=1 power them off and on again. 

Stream to the wired speaker.

Will do… that would be my arc.  Thanks!