You need to troubleshoot this problem with logic not guesswork
Take a laptop to the same location as the PC, turn off Wireless, connect the ethernet cable
If it works then the problem is with the PC (possibly a faulty Ethernet port/card on the MacBook which is shorting out)
If it still doesn't work take the laptop to the router and connect with a short alternative ethernet cable to the same port on the router.
If it works then possibly the long ethernet cable to the bedroom itself that's faulty - replace Or the wall socket is wired up incorrectly.
If it doesn't work then try another port on the router
If it works then probably the 1st router port is faulty
If it doesn't work then the router itself is the problem
Edited by rogerfp (Wed 30-Apr-14 16:55:23)