Can you tell us the following:
– NoMachine product and version on local machine, and also on the remote nodes (Workstation, Terminal Server Node etc. You mentioned only Cloud Server on the main server.
– Whether the problem arises connecting to a physical or a virtual display.
– Specific local OS version
– Os on the remote server and nodes. If Linux, desktop version (GNOME, KDE, etc) on client and on server.
Additionally the logs would be useful. You can extract using the following instructions: