I saw the checkboxes for blanking the physical console (but it didn’t work)
Is that a virtual machine? You need to know that blanking features applies only for physical monitors.
The NoMachine virtual desktop functionality is available on remote Linux host with Workstation, Small Business Server, Terminal Server, or Enterprise Terminal Server.
However, NoMachine is able to use its own display service (that is an embedded X server) to let users connect seamlessly a physical desktop running in background on the remote machine when that Linux host doesn’t have an X server running (e.g. a headless machine).
To disable Xserver you can for example use sudo init 3
command. After disabling Xserver – nxserver restart is needed (sudo /usr/NX/bin/nxserver --restart
).