The screenshot shows the result of the SMB mount: It is the directory structure of the ROCK.
But the ROCK now has 2 attached items under “Storage” as I described (but only one T7 SSD is attached).
I’m not the first with this problem - there are at least 2 similar questions here - but with no final fix.
Deleting and reinstalling the whole musiclibrary is not a satisfying solution for me.
This seems to be a Bug in the serversoftware.