because of my problems with ISP yesterday I got a bit angry at them because it was not first time when they messed configuration on their AP I'm connecting to. So, as the first I searched what can be used for monitoring my network and then gave a try to vnstat I haven't use before (ok that is not that new thing, but I simply haven't used that up to now because of ntop, netstat, ... so many tools in the area ;-) What vnstat does is that is collects traffic information for you via a service reading /sys. You can then export some statistics for various periods.

https://www.geeksforgeeks.org/vnstat-command-in-linux-with-examples/
I also learned about "ip -o -t monitor" which is way easier to use than checking logs and/or tcpdump when having connection issues

and then I was searching for some information about testing, monitoring, maintaining networks. I came across archive of NANOG talks.

I really don't know if it is interesting for any of yast developers and I didn't make to go through everything I wanted yet but this caught my eyes so far

using open source tools to validate network configuration (https://www.youtube.com/watch?v=D9hZiW66jw4)
a practical guide to (Correctly) troubleshooting with traceroute (https://archive.nanog.org/meetings/nanog45/presentations/Sunday/RAS_traceroute_N45.pdf)

btw for my next study & learn period I planned to find out what's new in network emulation area. I'll probably take this https://www.networkstraining.com/network-simulation-software-tools/ as a start point.

Michal