NoMachine's NX Free Edition Linux terminal client and the Synergy server don't seem to get along when running at the same time, at least on Linux. It seems to be a case of how the programs take over the mouse causes issues with sending mouse events through the NX Client. Not a big problem, as I can just run the NoMachine NX Client on the windows machine to the left while it's running the Synergy client without issue. Or shutdown Synergy server if I need to run the NX Client on the Linux notebook.