Sonos App Locks up on Android Since September 2021

You have clearly approached the troubleshooting methodically and knowledgeably.

There are a couple of things (at least!) that are really baffling me.  The main one is the nature of the failure.  The app freezing is very odd.  If the problem were to do with different subnets of wifi bands then I would expect an error message saying ‘cannot find Sonos system’ or ‘cannot connect’.  I would not expect the app to quietly refuse to cooperate.

The other baffling thing is that a controller running Android 7 is OK.  I thought Android 7 was not even partially supported on S2, but maybe I’m wrong (I will check)

You are correct, Android 7 says on it “not supported” but it works flawlessly.

I suspect this to be an app specific problem while it polls/scrapes the individual speakers but that is just a guess.

I can try a new subnet or alternate wifi (specifically one with only a 2.4 ghz band) as a test but it would be a shame to have to get a different wifi system just to accomodate a glitch.

What puzzles me is that this happened the moment that patch in September hit me.  Prior to that I had zero issues.

I am 99% certain if I could roll back the app and use it everything would work.

The only other troubleshooting I can think of to test is this:

1.  Try a different wifi router to test.
2. Remove all speakers and create a new Sonos system adding 1 speaker at a time every few days in case just one of them has a botched update or something on it (say, caused from packet loss).

I truly appreciate your time investment on this and I apologize for starting out harsh but I felt abandoned by the Sonos support team--and they are not all created equal.  I did reach an individual and I wish I recalled his name but he provided stellar support and did not suggest I just go out and purchase all brand new speakers.

I would love an error of some kind but I can try and monitor if it has a memory bleed or something but that bit of information won’t let me fix it but it would give me another clue what is going on.

Please would you try one further thing? Please connect just one Sonos speaker to the switch.. Uninstall the app on one of the phones then re download from Play Store and connect to existing system.

Can do.  By the way, do you care which speaker I use?  I did this in the past and it worked until I exceeded 4 speakers.  I will keep it to just one this time.

Also, after uninstalling app I “forget” the local network and reconnect to it after reinstalling the Sonos app just to limit the variables.

As another precaution I will unplug all of the other speakers prior to making a system of (1) speaker. 

I may not get to it until Saturday (due to work) but I will get it done.

It wouldn't do any harm to dial down the power on the 5GHz band as you suggested. Then connect phone while in another room from the router. (In theory this shouldn't make any difference.  But none of this makes sense!)

I have a sonos system up and running with just (1) speaker.  It works.  I can do what I did the last two times, and slowly build it back 1 speaker at a time.  But I will wait so I do not throw off your thinking/diagnosing.

After I get enough speakers on it locks up.  

As a guess, perhaps is the 5ghz cross-talk to each other that causes a problem with too many of them that causes the app to lock up.  But why would it have only done it after a patch.

So current position is one wired speaker controlled by one device / app? If so.…

Stick with the one app. Leave the first speaker wired. Power up additional speakers one at a time, wirelessly.  After each one is powered on, check in About My System. The speaker should have WM=0 next to it not WM=1.

Hopefully all speakers will add  and work. If so, then on each of your other phones uninstall the app, reinstall and connect to existing system. 

Let us know how it goes.

Further note. If you have any Move or Roam speakers, they will always have WM=1.

Thanks for the advice.  I have rebuilt the system as you suggested.

1.  Started with the very first speaker hardwired.   All future speakers were added wirelessly
2. All speakers are on WM:0  with the exception (thanks for mentioning it) the Move which is WM:1
3. I ran a test of having all (10) speakers running a different station for 15 minute which scrolling around in the app.  
4. I currently only have (1) phone and (1) pc connected to the new system to isolate any issues.  The current phone connected is one that had problems in the past.
   
   I suspect the next step would be to add other phones, 1 at a time and see if everything works unless you have a different attack plan in mind. 

That is good news. In fact the last step I have already suggested is to try adding the apps on your other phones to the system. Out of an excess of caution I have suggested uninstalling the app then reinstalling it and connecting to existing system. 

At the risk of jinxing things, I cannot think of any way in which adding further controllers can damage what you have already. The apps are just remote controls for the system and adding one should have no impact on the system itself.

But let's try it and see.