I can connect to my NoMachine server if I log in local graphical console
$ glxinfo | grep -i “renderer\|vendor”
server glx vendor string: NVIDIA Corporation
client glx vendor string: NVIDIA Corporation
OpenGL vendor string: NVIDIA Corporation
OpenGL renderer string: GeForce GTX 1050/PCIe/SSE2
so, it’s not using Virtual GL, it looks like a kind of screencast.
it seems I need to run a new session of Gnome (a new virtual desktop). Is it possible in the free version?