Oddly, I’ve never lost functionality on either my Mac or my iOS devices, all currently running S2. It makes me wonder if you may have a network issue, causing either your speakers to not properly communicate with the router, or your controllers not being able to reach the speakers to issue commands to them. At the least, I’d try a network refresh, by unplugging all Sonos devices from power, then rebooting your router. Wait two minutes for the router to come back up, then plug back in your Sonos devices to power. Wait another two minutes for them to boot up and reconnect, then open your controller to see if they are there. If so, check for updates and apply them, then you should be good to go.
If, however, this doesn’t help, I would recommend that you submit a system diagnostic within 10 minutes of recreating this problem, if you can, and call Sonos Support to discuss it. Don’t post the resulting diagnostic number here, Sonos’ lawyers get sensitive about GDPR, I suspect.
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.
