Yesterday, my mother-in-law had a cable modem installed so that she could video conference with us and see our son (she just got a new 20″ iMac the other day). Video conferencing is easier said than done with NAT routers. I’ve used a Linux box as a router for a long time so I have full control over everything; the problem is that having more than 1 person do a SIP based connection is tricky. I had my iptables setup to route SIP traffic to my Mac, so things worked fine. Well, UPnP on my Linux box didn’t seem to work, so I finally plugged a router right into my cable modem only to have mixed results. As a last resort, I plugged an Airport Extreme base station into my cable modem and presto, everything started working. So while Apple’s router costs 3 times more than any other home based router, it sure is worth it as I think I spent over 8 hours to fix this issue. Below is a diagram of my wacky network; it is a bit strange in order to have my server running and have the Airport Extreme base station working. I’m almost surprised it all works. Networking is an art, not a science.