Hello ang,
NoMachine Free has licence that allows only for one connection
to the server. If You suspect orphan connections please check
output of commands:
/etc/NX/nxserver –version
/etc/NX/nxserver –list
/etc/NX/nxserver –history
To investigate possible issue with error logging in or a black
screen please follow the instructions here:
https://www.nomachine.com/AR07K00677
Please send logs and output of commands to issues[at]nomachine[dot]com.