Ethernet port test?

I recently transferred a bunch of data between my windows computer and new macbook pro via directly connected ethernet, via a dock for the macbook pro. I've never used the direct ethernet before but all worked fine. BUT I noticed, on a few occasions, the macbook lost connection to the windows' shared drives and prompted to disconnect all. I assumed this was related to direct connection, or windows/mac being finnicky.. or whatever. However, now I'm starting to wonder/worry about the ethernet port potentially being faulty. I don't yet have my "desktop mode" fully set up, and so I'm not regularly using the ethernet port extensively just yet. Is there a way I can do a test on the ethernet port? Basically, I assume, keep a connection alive or transfer data or something AND monitor/flag for issues?