We have the same behavior with Windows but only when running NoMachine as a specific user. If we run NoMachine as any other user it works fine and does not immediately disconnect. I’ve looked though the logs but we don’t have any screen size errors.
I’ve tried reinstalling different versions but that specific user account always disconnects immediately after connecting. Is there some user specific configuration that does not get cleared during uninstall? Initially it was working on that user account until updating NoMachine. But now it does not even work when we reinstall the old version.