RJ-45 corrosion

Something to check if you are having network connection issues, shine a flashlight into the RJ45 socket to check for corrosion (or pin damage).  I see this a lot on floor jacks and in restaurants.

Any place where the jack would be exposed to moisture.  Another problem is grime build-up.  This happens a lot in commercial kitchens when oily steam permeates the air and condenses on the pins inside the jack.