use arduino to diagnose probles with network

OK I have a home network as follows:
4 PC's running windows
1 file & web server (ubuntu 14.04)
1 laptop ubuntu 12.04
1 laptop Linux mint
1 arduino datalogger

I have a spare Uno - (and happy to get an ethernet shield) can anyone point me at information that will help me put together a simple device for doing tests on the network?
I really just want to get a better understanding of how the ethernet works by experimentation.

What specific tests do you want to do?

Weedpharma