I think we are not 100% sure why he is actually being disconnected.

The network diagram that Mikekim did is exactly what I would do.

Sam's point of talking to Blizzard is also good. Their tech support is usually pretty good and most of them would probably geek out at trying to find a solution for you. I know I would.

Email: wowtech@blizzard.com
macsupport@blizzard.com

Phone: 1-949-955-1382
Hours: 8AM – 8PM Pacific Time, Monday through Friday (excluding US holidays)