Remote graphical desktop with DGX-A100 server

We have a DGX-A100 server, updated to DGXOS6.
We need to install the Ubuntu graphical desktop because some people need remote graphical desktop. We have no need to use the base console with graphical desktop, text mode is ok.
I installed the desktop following suggestion on internet
(# apt install ubuntu-gnome-desktop)
The desktop works perfectly with remote access (we use VNC via ssh tunnel). Anyway, after the boot now the console freezes, no interaction possible, even if the rest of the system is up and running.
As, written, no need of a graphical console, just the chance to use it, in text mode.
Has someone tried desktop installation on DGX-A100 server?
We were not able to find where is the problem from the system log (probably because no-one of us has deep management experience…)
Any help is welcome