Hard to tell, but my initial thought is the router.

Power down your phone completely. Do the same with all Sonos devices, then reboot your router. Give the router a minute or two to restart, then power back up your phone, then your Sonos devices. 

On the other hand, you could have other network issues, so it might help to know what router you have, how the Sonos connects to your LAN, and which Android OS, and which Sonos controller you’re running. 

Thanks Bruce,

My Sonos connects via WiFi. The phone is Samsung s21 running Android 13 5.1. the router name is icotera i5801-01

Must say I'm a bit novice with IT

Will try your first suggestion but probably won't see the results until later. As I said, a router restart fixes the problem (temporarily)

Is the set up sensitive regarding 2,4 GHz and 5 GHz? Without being absolutely sure I think my system runs 5ghz

Tried the reset procedure but it did not help. After being disconnected form the WiFi for a little while, it failed to connect again

Hmmm. So it’s not likely to be an issue with duplicate IPs, as that process would have cleared that up, at least until the next software update.

I’ll admit I’ve never heard of an icotera router before, but generally speaking, use of 2.4Ghz vs 5Ghz shouldn’t make a difference. I tend to stay with 2.4Ghz for superior distance and penetration, there just is no need for the extra bandwidth of 5Ghz for Sonos. Nice to have the option, just no benefits. 

So my thoughts lean toward wifi interference . Although I’m not convinced. I think your best bet at this point is to submit a system diagnostic within 10 minutes of experiencing this problem, while your system is ‘connected, 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, they have tools at their disposal that will allow them to give you advice specific to your Sonos system and network.