What type of mobile device do you own?

What does your network consist of?

Do you use extenders or powerline adapters?

Do you use a VPN? If so turn it off.

Do you have any speakers wired?

The more information you can provide, the greater the possibility of finding a solution.

Samsung S24 Ultra.

Vodafone broadband. Wireless router. Extender does exist, but not used with sonos. Sonos and phone on same network (not extender). 

No vpn.

No speakers wired. 

3 sonos one. All on wireless. 

App just had a mind of it's own. Does nothing I ask it. 

I've managed a work around via Spotify app. But I just used to enjoy using the sonos app. Now it's totally unusable. 

Hardwire a speaker to your router to see if that solves your issue.

Sometimes wifi is all you need but sometimes, Sonosnet works better for some users.

Cheers but hardwiring is not an option. Neither Home layout nor desired aesthetics allow.if id wanted a wired audio set up, I'd have probably chosen a different brand. The whole point of the Sonos eco system is wireless speakers working seamlessly. 

It used to work perfectly, and now it doesn't. So it must be the app. It has no usability and no functionality. It's just so buggy and I don't no why.

Is there any way to roll back the app a couple of years via APK? 

Wiring a s single speaker, even temporarily, is still a sensible suggestion from ​@Pools-3015 .  Sonos was designed to work with its own mesh network, as in those days most domestic WiFi could not cope with potentially large numbers of sync’d speakers.  Or even small numbers of speakers.  A single wired speaker is required for this setup, so that data can flow between the home Wifi and SonosNet.

This still works best for some users, so responding with sarcasm to a person offering sensible advice in their own time is rather ungracious.

Incidentally, I have no problems with the app on my system, so I don’t think your experience is the new normal.  It may be that my experience isn’t the new normal either, of course. But the app is just a remote control for the system.  It is not the source of your problems.

Apologies if I came across as ungracious or even possibly obtuse. I was at the time about to drop kick my sonos speaker out of the window after it failed to do anything I requested when I just wanted to listen to music whilst cleaning. I misunderstood the temporarily thing. I figured he meant permanently. Potentially I could wire one up to see if it helps, but it would really have to be VERY temporarily as my home layout and router positioning would cause a ballache. I only have 3 Ones, and nothing else has changed other than the app updates. It used to work fine and then didn't. And all Google showed me was people berating it so I assumed it was the app. Even looking on Sonos advert comments, all you see is moans. So something must have happened. 

If you go into a hospital, you will find an unusually unhealthy population.

Clearly there have been significant problems with the new version of the app, but much has now been addressed.  And I get the frustration when it won’t work and you can’t fix it.  And it should work.

For some people a good solution is to wire one speaker permanently.  Ok it isn’t for you, so we look for another solution.  I’m not sure why wiring one speaker temporarily for diagnostic purposes would be a problem.  What is worse than none of your speakers working?  I suggest you try it and see how Sonos and the app perform.  I would power off the router and all 3 Sonos speakers, wire one (preferably the one currently furthest from the router, but not critical).  Then power up router, then wired Sonos, then other Sonos.

I am also interested in the extender, despite your being certain it is irrelevant.  Could you please provide more detail on your network setup and the extender’s place within it?  Is the extender set up in “access point mode”, aka “bridge mode”?

Even though Sonos is marketed as a “Wireless Audio Solution”, Until the Era and battery powers speakers were introduced, there were ethernet ports on all devices. This was to enable users to hardwire one or more speakers to their network incase there was an issue with their WIFI. Initially using a “Bridge” was the only way to connect Sonos to your network by creating its own network called Sonosnet. This device was HARDWIRED. Then Sonos made it possible for you to use one of its speakers , or Connect/Connect Amps instead of the Bridge. This setup also used Sonosnet for connectivity.

I have always had one or more speakers hardwired to my network and never had ANY connection issues. The new app also works like a dream for me because I have a very good connection to my network. I have 11 speakers in my home with 6 of them hardwired.

Wire one for a temporary try.

Get everything on the latest releases. Power down all Sonos and reboot the router if you have a problem with that.

If it works you might try assigning static/reserved IP Addresses for all Sonos. Power them down, unhook the Ethernet, reboot router and power back up.

Thank you all. I'll dig out a cable and try the suggestions. 

Great. Between you, the many knowledgeable people on here, and if necessary Sonos Support, I am certain we can get your system working well again. Please stick with it.

Well... Plugging one in made it work OK for a day or so. But now it's back to "something went wrong" more often than not. Unresponsive app etc... Not doing what it should.

Pretty much as bad as it was before and it's still plugged in. 

I’m no technical expert but I suspect this is something to do with Vodafone Broadband.  I recently switched to Vodafone Broadband and now my Era 100 is constantly disconnecting and reconnecting but my Beam (gen 2) and Play 3 all seem to still be working fine.  I hardly ever had any issues before I switched to Vodafone broadband. Unfortunately with Vodafone broadband they don’t seem to let customers edit the wifi settings too much. I’ve tried switching on compatibility mode but that doesn’t seem to have helped much for me.