cutting in and out - but only on Amazon UNLESS I ask Alexa to play the same thing!

It may be the lead device in your group.  When you create a group within the Sonos App, the first device co-ordinates the synchronisation across all of the grouped players.  If possible can you test this by ungrouping all players and then selecting either a wired player or one closest to your router.  Make sure that is playing okay and then add the devices to that player.  Let us know if this improves things.

Thanks, I’ve just tested this and the first speaker alone works fine, as soon as I start adding more in the issue begins. I’ve got a high end access point that I’ve placed in the same room as all the devices, I’ve also swapped out this access point for a different one, and tried just using the Wi-Fi built into the router. I’ve run some Wi-Fi tests, there are no overlapping channels in the area and my access point support DCS.

Are you able to connect one of your Players via an ethernet cable and then remove the wi-fi credentials?  This will create a Sonos mesh network and may be better than an AP.

let me try that now

no joy, same issue. Only with Amazon Music though. If I ask for the same album via Alexa or anything like TuneIn radio or even Sonos Radio its just fine

I've flagged to Sonos to investigate your diagnostic. Probably best to wait for their investigation now.

Hey @jamescodefour,

I’ve taken a look at your diagnostic and I can make the following observations:

• There is indeed a difference between starting playback via Amazon Music via the Sonos app and requesting playback via Alexa. When using the Sonos app the speakers are requesting FLAC files, but not so via Alexa. This will definitely increase the data stream from player to player as FLAC files contain a lot more information than their compressed counterparts.
• The speaker that leads the group, or “group coordinator” (GC), is important when playing music in more than 1 room. We’d ideally like to see the player with the strongest WiFi signal (or a wired unit if present) to be the GC to ensure a more stable connection. For you, that’s your Beam + Sub. Try ungrouping your players, and instead of hitting the group button next to your Play:1, instead select the Beam and group from there.
• Your players have good connections between themselves, so I don’t suspect there’s an interference problem or a player-to-player issue here.
• If possible, please try wiring one of the speakers, and use that as a group coordinator, just to see if that makes any difference at all (provided the previous test yields no results).

I hope this helps! Let me know how you get on.

Thanks for flagging @UKMedia 

Thanks James, very helpful and interesting about the different formats. So I did as requested and set the Beam (TV) as the lead speaker and played successfully on this alone. I then added the next closest, and the next until the 4th speaker (play:1 Dining room) and it all went pear shaped again. The thing is I get the same issues even when I put all the units in the same room and put the access point in the same room. Nothing has changed network wise. I’m getting 35mbps download on FTTC with single digit latency. My access point is a Wi-Fi 6 high throughput enterprise model (Zyxel WAX650S)   

Hard wiring ins’t a solution for me (even just one unit).

Any other ideas? I’ve updated the diag - 667178478

Thanks Richard, my observations are almost identical. I hadn't thought about what model of speaker at any point but you're right, the only ones that skip are the Play1’s. All the others, regardless of distance from my Wi-Fi are fine. They are The 5, the Beam, The Roam etc only the Play1’s are skipping