Users are unable to connect when NoMachine is installed on host that is also an Active Directory client.
In this case the session negotiation fails with:
Error: Cannot authenticate to the requested node.
This problem has been reported affecting a NoMachine server 4.3.23 and 4.3.24 installed on a Windows 7 host.
A similar problem occurs also on Linux platforms, the correspondent trouble report is:
https://www.nomachine.com/TR10L04640