The current network disruption (from around 2:30 p.m.) has been fixed.
There may still be restrictions on individual services afterwards.
Note about the CAT tool:
At https://www.geteduroam.app you can find the tool for Android, iOS and Windows.
After starting the tool, select the "Hochschule der Medien", select the certificates that are not yet installed (in most cases this should be "eduroam Service Root CA") and log in with