thanks, but currently I only have one phone, so I then cannot steer the Sonos system, because the Sonos App on my Android does not work if I have Wifi turned off. Sonos App on Mac does not have network settings as far as I seen.
For now I grouped the speakers in Sonos app and this works and its shown in Spotify as Play1 + 1.
What else could I try? If I ungroup the speakers then it isn't shown as well. It looks like Play 3 disappeared from the grid completely and it worked normally for years. Could be because of some update?
Play 3 not displaying might indeed be related to an update either to the Sonos app or the device firmware. You can check if there are any updates available for the speaker and enable those.
Regarding the network test - when you create a Mobile hotspot what happens is that your phone creates a WiFi network using your mobile data. You can then connect the phone, computer and the speakers to that WiFi.
Let us know how you get on with this.
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I have tried this approach and used one of my Play1 as a router to rebuild the Sonos network. It was not helping. But when I reconnected Play3 and again use it as a Sonos router, so now I can see 1x Play3 and 1x Play1 in my Spotify Connect. So now the other Play1 disappeared.
Just before trying this it got even worse - in the morning I have only seen one Play1 (and not 2 anymore) in Spotify connect. I do not know what else to do? This is really frustrating.
To sum up: - I use 2x Play1 and 1x Play3 setup, have only 1 wireless network - playing Spotify via Sonos app works fine on all speakers - I use Spotify & Sonos app on Android and Mac - Spotify Connect shows my Android phone, my Mac and one of Play1 speakers (after "rebuilding" my Sonos network I can now see Play3 and Play1, but now one Play1 is missing) - grouping: if I group the missing speaker with the one working via Android Spotify app (redirect to Sonos App) and then ungroup them, trying to play only missing speaker will stop playing music - I have clean reinstalled both apps on my Android, the same problem - I have reset my internet router - I cannot setup a separate hotspot at this moment, because I can only steer Sonos system via my Android app - if my phone serves as a hotspot I cannot connect to Sonos