There are a couple of potentials that leap to my mind, one resolvable easily, the other potentially not so much.

The easy one is a potential duplicate IP address, which can’t normally be “seen” by looking in the router’s DHCP table, as it only presents what is connected at the moment the report is run, and doesn’t show changes over time. An easy test would be to unplug the CONNECT from power, then reboot your router while it remains unplugged. Only once the router comes back up should you plug back in the CONNECT. Do some testing. Does it still cut out? If not, we’ve identified the issue, which is rare, in the grand scheme of things. You can do that process again if it happens again, or you can look at your router’s manual on how to set up reserved IP addresses in the router’s DHCP table, and do that, which will keep this issue from recurring. 

However, it’s also possible that there’s an issue in the electronics of the CONNECT that’s causing it to fail periodically. Could be overheating, could be some other issue, it’s hard to know without looking at a diagnostic, which is only available to the Sonos folks anyway. So I’d recommend that if the above paragraph doesn't fix the issue, you submit a system diagnostic within 10 minutes of experiencing/recovering from this problem, and call Sonos Support to discuss it.

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

When you speak directly to the phone folks, there are more options available beyond just the diagnostic analysis. 

Thanks for the response, Bruce. Much appreciated. I’ll give that a go now. Fingers crossed!