I have been understanding why the X server responds to the client's TCP establishment request Y with the RST / ACK flag. I think the problem might be one of the 3 below.
After the above points, the question is:
How can I tell if the port on the Server side is closed? I note that sometimes the connection succeeds ...
How do I know from Wireshak that the package is malformed?
Is the firewall bus internal to the client network or to the server network?
Most likely, there is no application waiting for connections on that port on the target server. The fact that "sometimes" the connection is successful indicates that "sometimes" the application on the target is in the air.
It could be some firewall problem, but it's hard to figure out there, it's hard to know what's in the middle, unless you control the environment as a whole.
It could also be malformed package due to hardware problems, some network interface, but I also do not believe it.
My guess is that it's an even operational problem: not always the destination application is in the air.
