In my setup the server is my private home server and the client is my work laptop. I suspected that the problem is related our enterprise security policies, which are allergic to incoming connection to our devices. Therefore the server component of the free Windows software is a problem. I do not need the server on the Windows system. I uninstalled NoMachine free version and downloaded and installed the Enterprise Client. From what I can see it is basically the same client, but without the integrated server. This seem to work. I did now use it for a few hours without any freezing or other strange behavior. It is actually very responsive even in higher screen resolutions.