How to understand where the problem is in the network, and is it exactly in it?

Question

Computer networks

Good afternoon,
There is a certain system that works as a client-server. The server and the client application are hosted in different ESXI virtualization environments and there is an IP/MPLS segment between them.
The essence of the problem is that the client slows down at startup, and the connection is interrupted periodically.
When running the client locally on the server with the system, there is no problem. Pings pass without loss.
I sniffed tcp packets, and compared a successful connection with an unsuccessful one, found a difference in the TCP connection analytics graphs, apparently this is the problem, but how to understand what the problem is? (on the left is the problematic session)

Answer 1

Any problem, especially in the network, is searched for by the elimination method .
To do this, make a global assumption, and try to refute it. For example, it could be either the client or the server, or both. Checked - excluded something - further narrow the circle of search. And so on until you get exactly to the cause.
Meditating on graphs and trying to understand them through telepathy and psychic abilities is not a sure way. Sometimes insight comes. But it is better not to rely on luck, but to follow the proven path, extracting more and more information that helps to exclude many options at once.