You might try setting static/reserved IP addresses for your Sonos using your router’s DHCP page and then powering down your Sonos, rebooting the router and powering up the Sonos.

With all wired that is all I can think of.

You might contact Sonos support with your diagnostic, it may be seen here but staff presence here in the user-to-user forums is limited.

Annoyingly, still having the issue. I tried connecting all devices to ethernet and assigning IPs, and have now reverted to wifi only. This seems to happen with whichever device is “controlling” the audio -- so, the device which is downloading the audio, and distributing it to the other amps. I have 5 connect:amps in total. Audio mostly cuts out in last 25 seconds of songs, while it is loading up the next one… and the other amps will continue to play just fine (which is completely counterintuitive, but there we are...). 

EDIT: I have confirmed that whichever connect:amp is downloading/controlling audio will experience the dropouts. So bizarre. Again, the other devices will play the audio just fine… the best summary I have so far is, “my sonos connect:amps cannot download music and play it at the same time….” :/ 

Hi there.  Did you resolve your problem with drop outs? I have the same problem with 2 connect amps.  

Same exact set-up here and experiencing the same issue.  I have been in touch with tier 1 support a dozen times and tier 2 a few times.  Plenty of suggests, but nothing resolves the issue.  The problem is certainly worse over the last three or four months.  

Same here. I have 12 devices in 9 rooms. We listen mainly to internet radio. We get intermittent drop outs.in most rooms. I have not yet isolated common themes, but I have noticed it is worse when I add another device to play the same content in more than 1 room. 

Devices also appear to fall off the system and have to be switched off/on to get them to re-attach.

For us, this issue is getting worse and has probably been more noticeable for 3 or 4 months.

Any suggestions?

That sounds like you’re on the edge of wifi interference , so that one stream seems to play, but as soon as you ask Sonos to add another speaker, it goes over the bounds of available clean bandwidth, and starts breaking up. 

Sounds like it might be this Issue