If it’s a headless Linux host you are connecting to, please follow the tips in the article here https://kb.nomachine.com/AR03P00973, specifically 1) Use a X virtual framebuffer.
Better would be to disable the display manager permanently, then the DM won’t start after reboot. This is the command
to disable and stop the DM:
sudo systemctl disable --now
[enter here display manager]
sudo /etc/NX/nxserver --restart
(just once, after reboot all will be fine)
Now when you connect, you should be able to start your session correctly.
If that doesn’t help, please submit the following information:
– NoMachine product and version on local and remote machine (free version, Workstation, etc).
– Whether the problem arises connecting to a physical or a virtual display.
– Remote and local Windows/Mac/Linux version (Windows XP/7/8, OS X 10.x, Ubuntu xyz, Mint x.y, etc.).
– Desktop version (GNOME. KDE, whatever) you are connecting to.
When you connect, are you seeing a black screen with a moving cursor, or are you seeing the desktop’s content which is frozen (except for the cursor). Is there a specific application running?