Hi @Martin.Jirsak , there was recently a thread in the German forum about a similar problem.
Audioverbindungen bei Gerätewechsel weg? - Auf Deutsch / Cubase - Steinberg Forums
I made a test:
Set up an external instrument (first set up as a MIDI device, then set up the audio connections).
…
Then Cubase closed and opened again - initially without a project.
As usual, the input and output connections only show one stereo channel each, but the external instrument is there, as in the picture above.Then I switched off the interface and restarted Cubase. The “Audio driver settings” window appears.
After switching on the interface and without loading a project, the external instrument is still available in my audio settings, but without a connection to the audio interface:The audio inputs are also not connected, while the audio outputs have not lost the connection.
When I then open a project template, all input and output connections are there again, as they were saved. On the external instruments, however, the device ports are not connected and I have to set them up again manually.
You can find the corresponding screenshots in the thread mentioned above.