I can control the SoundTouch 30 via Windows 10 app and iPhone App in regards to settings, Radio and on/off but I can not play Spotify any longer. It says "Zur Wiedergabe bereit" but when I select a song in the Windows 10 SoundTouch App it changes to Laden... and stays silent. Same goes for Spotify.
That happened when a second iPhone App and computer connected today.
Connecting multiple devices should be possible rightß
Thank you for posting and welcome to the Bose Community.
Yes, you should be able to connect as many devices as you would like to your SoundTouch account without limitation. Seems very odd that you're running into this issue with Spotify though and I'd like to help you figure this out.
Can you test by removing your Spotify account from the SoundTouch app and then add it back as a source?