Hi @dejavu,
to avoid conflicts with existing key reservations I used a softboard from Virtualbox. CTRL ALT F2 does nothing when I am in the graphical mode BUT returns me to the graphical mode if I am coming from the login prompt. So existing key reservations shouldn’t be a problem. I Also testet UCS 4.4 with the same result. Might there be the problem that root login is permitted until I set a password for Administrator? I think other Linux distros do not allow logins as root user until there is a second user with a password. Anyway there is also another article where a user reports that the login with root/univention shall be working: NetBIOS Namen bei der Installation festlegen