Few years back, I worked as a wire/cable installer, running LAN and phone cables. I knew a bit about PC, but just worked with the passive system (cables).
Had a lady complain that she "couldn't get on the network". So, getting my cable tester, I walked over to her workstation, and saw a blank monitor. After checking the plugs and cables, checking the PC and monitor power, I said that her monitor was broken.
"Well, you're working on the computer lines, can you fix it"?
Me: "No, you need to call your IT guy. Your network cable is fine. I don't fix monitors."
She calls someone else on the phone: "I can't get on the network. There is a guy working on the computer wires, and he doesn't know what the problem is."