I have a setup here where my Mac Pro receives a wireless connection from my Aiport Extreme N station, then (via the two built in ethernet ports) shares the internet connection with two older Macs. However for a few days now my Built-in Ethernet 2 port doesn't seem to be working correctly. It isn't sharing my internet connection, and it also isn't showing up in Network Status in system preferences (although Built-in Ethernet 1 is). Also, when I switch which port the two computers are plugged in, the same thing happens, and they switch which one gets ethernet. I do have both ports enabled in network port configurations. I also have both selected in sharing preferences. I've also started and stopped sharing preferences. Not like that would matter since the port still should show up if it has something plugged in.