I'm using the Nomachine version 3.5 NX client on my desktop system at home to connect to a FreeNX server at work. The connection is responsive most of the time, but my session hangs for 3 to 10 seconds now and then. Then it resumes normal activity, and all is well again for a while.

There doesn't seem to be any pattern to the slowdowns. I may go 10 or 15 minutes without a hang, then I might experience several hangs within a few minutes time, or even spaced just a few seconds apart.

I normally have a KDE desktop with a couple of Konsole sessions running over NX, along with two or three X3270 sessions. Rarely I'll have a git gui and an emacs graphical editor or two active. But mostly its just Konsole and x3270. There are no heavy graphics or multimedia. I'm not using the KDE desktop for anything other than hosting the Konsole and x3270 sessions.

The system running the FreeNX server is not running a demanding workload. The CPUs are 95% or more idle most of the time. There is an ssh and a vpn server running, but they not very active either. The biggest workload is a hercules emulator, but it's not very busy either.

My desktop at home is old and somewhat constrained in RAM, having only 4GB. Firefox is usually the biggest resource consumer. But again, top shows very little going on whenever these NX hangs occur.

What can I do to try to figure out where the delays are coming from?

I'd watch network by some app or a few apps to start.

The only way to rule out completely might be to create a local lan to simulate this exact setup. I'd assume it would work OK but you need to test or start at some place.

The only one I'm even a little bit familiar with (which is not saying a lot) is iptraf. Even if I see a delay in the monitor, how do I go about identifying the cause?

Also, I think that iptraf can only see what is coming into or going out of the system it is running on. I guess I could run it on both sides, on the NX server and on my desktop. But the delay could be somewhere in between. What exactly should I monitor with it, and what do I look for to identify a delay?