Not much information to go on, but I’d try a reboot of both the Sonos and the router. I’d also temporarily wire a Sonos device directly to the router with an Ethernet cable. Finally, I would recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it. But don’t post the resulting diagnostic number here, they get sensitive about GDPR.

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 Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

We have the same issue. Long time Sonos user (probably had one of the original systems). They have bricked a number of devices (controller, stereo connector) but up until a few days ago, we were able to make it work using the S1 App for everything but the God awful Roam (maybe the worst bluetooth speaker on the market. Impossible to connect and when you do it sounds like shite). 

When I logon to the S1 app it does not find my main system but instead connects to the Roam (which I find humorous given how difficult it is to get the Roam to connect to any other device or app).  There is not option to ignore it, etc and it “forces” the use of the S2 app, which I also have, if you choose to connect (only shows the Roam).

I am pretty much done with Sonos at this point. There are other in home systems that are cheaper and better from a sound standpoint and with Bluetooth being easy to use on most systems other than Sonos, who needs the headaches. 

If there is an easy solution, please point me to it. But if the solution is me rebuilding my home network architecture every time I turn on my Roam device, then consider me a former Sonos customer. 

I could probably retire if I had a cut of all the Sonos systems I have sold over the years based on people seeing it at my home first and me promoting what a great service it is (was). 

Any advice before I chuck the entire system in the garbage? 

Problem all solved.

Our system is 12 yrs old and we use the S1 app.

We ended up un plugging everything, rebooting our wifi router and waiting for 10 minutes. Reconnected everything and it is now working. ‍♀️