To eliminate any network issues can you follow the steps in my article:

Please check the app permissions of your Sonos App and make sure that the local network permission is enabled. And try to reboot the phone also. After the reboot, check your Sonos app and open system setting if the application will detect nearby system. If you got connected, check for updates for your products. 

UPDATE

yestersay I told the App to forget my system, logged out of the App, deleted it, did a factory reset on every product I have, rebooted my router and set up my entire system from scratch, added Apple Music  and enabled Alexa on all compatible products. 
 

after doing this I was able to select a speaker and play a track okay. However today I opened the app and the app didn’t open correctly So I shut down my phone and switched it on again and the Sonos app still didn’t open so I deleted the app and reinstalled it and it found my existing system. However when I tried to play a track the play button just span around and then I got a notification that “the URL was bad”

I am at a total loss as to what to do I have 5 Sonos product that I am unable use any of them at all despite factory resetting the entire system. 
 

attached are some images showing my system in the app and the front screen which isn’t connecting to anything. 

Play button just spins when selecting  track which never plays and the. I get a notification saying “bad URL”

I get the same.  Had this a few times now. 
 

The saving grace is that local library is available. 

I have the same promlems

Same issue here. Since the app “upgrade” a few months ago this is a nightmare 

Same problem too. This situation is embarrassing. It’s really incredible that after so many months, the app still hasn’t improved.

Same here. This sucks

Same issue here, so I assume this is a general Sonos problem. Rebooting my phone helped, for the time being. So I suppose Sonos will have to fix it in yet an other update. It’s the second time in two days, since I installed the last update (version 80.11.39). 

Now it works!!

Same problem for me. After several app reboots and a phone reboot it works now. 

With all the s***** connection problems so far I would strongly recommend anyone thinking about Sonos to think agan and select something elese without constant problems

Moderator Note: Modified in accordance with the Community Code of Conduct

Thanks for sharing, Antonis. We will see if the problem persists over the next few days. Now we can assume it’s probably the app that causes the issue, and we don't need to spend time reinstalling the system (unless Sonos would recommend to do so after investigating). 

I suspect it’s not the app but backend Sonos infrastructure. Rectifies itself without an app restart or re install. 

Same here.

i cannot switch between my speakers with the app.

always unable to connect. Total BS.

To add to this pain the app didn’t even become better or more user friendly with the last update. Now it’s just messy. Previously I was able to switch speakers or rooms much easier. No the start screen is cluttered with unnecessary nonsense.

But bad UI is one thing. Not being able to actually command your devices through the app is a new low.

@Sonos: Fix this please

Agree, I can’t figure out how to play one channel one room, and another channel in another room.

 Swipe up from the Home screen.  Choose a Room.  Start content.  Repeat the process for a different Room with different content.