It looked plugged in
I've had a similar encounter, though in my case if you just peered behind the computer it LOOKED plugged in on that end. After feeling around it turned out it WAS plugged in, but only the plug! The cable itself had mysteriously disconnected from the end and was dangling behind the desk on other cables out of view. Some other cables lined up so that when you peered behind the case to just look, it looked just like the network cable was in place.
Biting the hand that feeds IT
