It’s strange that Server settings just suddenly disappeared. That would only happen if you removed the software and then made a new installation with Enterprise Client package. For example, you uninstalled NoMachine and then downloaded the Enterprise Client (no server included) and installed that?
From the system tray, click on the !M icon and select ‘Main window’ and go to Settings. You say you don’t have the Server component there, so click on Player and go to Updates. What is written there? If you don’t have any icon in the system tray, open NoMachine from your programs menu. You can also take a screenshot and submit here.
By the way, we also released 8.11.3 today, so you could uninstall your current NoMachine package and make a fresh installation using the NoMachine package for Mac.