sonos app is not working

Not enough information to make great suggestions.

I’d start with a simple network refresh, by powering off all Sonos devices, and the rebooting the router. Wait two minutes for the router to come up, then power on the Sonos devices, wait two minutes, and test.

If you’re looking for a more educated response, we’ll need to know details about what Sonos devices are in use, particulars about which Sonos OS is in use, where your controller is running, the OS on that device, and details about your network. Perhaps more. 

If you did a factory reset of your SYMFONISK you will have to do the initial setup again once you get tne app working.

Factory reset is not recommended unless suggested by Sonos support.

Delete the app, reboot device and reinstall. Never had this problem with Sonos app but similar problem on other apps and that has fixed the problem.