Using NoMachine version 4.2.26 free version on three machines.
-Windows 7 with server turned on so a client can connect to it. Using a physical display not virtual.
-Linux Debian machine A Mate desktop, with server turned on using a physical display
-Linux Debian machine B KDE desktop, with server turned off and only using client to connect to Win 7 and linux machine A. Also has physical display.
-The Windows 7 machine can connect to Linux machine A that is running the server
-Linux machine B can connect to linux machine A that is running with the server turned on.
Both linux machines can start to connect to the Windows 7 machine as after a new install (on the Win 7 machine) it mentions about a change in the fingerprint and credentials. However once you try to connect from either of the linux machines it simply gives you a message:
<no available sessions on this server>
IF you click that link it says:
The server was unable to make the local display available or access to the local display is disabled.
How do I fix this problem? It was working fine before I upgraded.