Which network stability monitoring utility to choose?

Question

Computer networks

Hello, we have our product installed in a client's private data center. From time to time, connections to the database hang for minutes, but then they successfully hang. Other customers do not have such problems with our product.
Hangups occur periodically, several times a week. At the same time, customers see that our product works poorly and slowly, and sin on us.
We have a strong suspicion that something strange is going on with the network, and would like to use some kind of network health monitoring to make beautiful, understandable graphs and suggest that the client gobble up their IT department, not us.
We have access to machines in the client's private network, we can install something. Opening the port to the outside, or sending something out - will not work. The monitor must work within the network, you can look at its UI, if it exists, through the tunnel.
Operating system - Ubuntu.

Answer 1

What do you mean by the concept - network stability monitoring?
There are probably some metrics, some parameters that you would like to track and build beautiful graphs?
Formulate TOR (not necessarily here, maybe even just for yourself) and see how it is implemented.
There are monitoring - zabbix, nagios
There are all sorts of charting tools - prometheus, grafana, cacti, smokeping....

Answer 2

Take zabbix and put zabbix client on servers/workstations in active mode - port forwarding on the client side is not needed.
Well, there, further, stir up the monitoring of whatever your heart desires.