First of all, sorry for my bad english
Now to my problem.
After resetting my local network (Fritz!Box Router) I got the problem, that the current spotify android app didn't show any of the connected (Teufel Raumfeld) speakers, which i could reach formerly without any problems.
Of course the speakers were integrated in the same network and they can be controlled with spotify connect.
So i rebooted my phone, uninstalled the spotify app, installed the app freshly and logged me back in without any success.
Just for fun i than opened the spotify app on my computer (Ubuntu), logged me in with my account and was surprised, that i could reach my speakers there without any problems. Even my android device was found here.
After that i switched back to my android phone, logged me out of spotify and than logged me back in with my account. Suddenly i could reach the speakers there as well.
So far so good.
So i tried the same thing with my wife's android phone and her account.
Unfortunately i didn't have any success there reaching the speakers.
So i tried all the here written troubleshooting steps, which didn't help.
For example I tried logging her out and logging in the spotify app using her account, which didn't help.
I closed the spotify app, cleared the spotify app cache, uninstalled the spotify app, deleted the folders in android, installed the spotify app freshly and logged her back in, what didn't help as well.
Then i just for fun logged her out and just logged me back in in with my account on the same phone.
I was more than surprised, that i could suddenly reach the speakers.
Logging me out and her back in with her account ended in the same result, that i couldn't reach any speakers.
So my conclusion is that there has to be an problem with spotify connect and different accounts, since:
Case 1: Using android device A, being connected to WiFi network A, using spotify android app A, logging in with spotify account A, i can reach the speakers with spotify connect
Case 2: Using android device A, being connected to WiFi network A, using spotify android app A, logging in with spotify account B, i can't reach the speakers with spotify connect
I'm looking formward for any help, since i have no idea what to do next.