Hi cperry,
which browser are you using? Does your password contain special characters or spaces?
It would be also useful to know:
– Which is your NoMachine server version.
– Which is the operating system and version of your server host (Ubuntu xyz, Mint xyw)
– If you are connecting to the physical desktop or if you are creating a new virtual desktop.
– Version of the desktop (GNOME; KDE, whatever else …).