Hi @Tim_Sahr,
Thank you for the clarification, this is much more clear now! I took a look at your experience and I believe you are missing just one thing to limit the displayed devices by userGroup. Just as you did previously, you will have to set the dashboard context for your userGroup tag context variable:
Because this is not set, the userGroup equals *, which will display devices with a userGroup tag. I believe the Dashboard Context should look like so based on your use case:
This will grab the User Tags for the logged in user, and references the userGroup value specifically. I would recommend double checking the path for userGroup by looking at your user object in the debug panel (as I guessed your path as pageData.experience.user.userTags.userGroup based on my own debug panel 
):
Let me know if anything is unclear, or if I can help further!
Thanks,
Julia