I just replaced my old MBP with a new i7, everything is working save for this (so far). I de-authorized the old machine, authorized the new one, selected home sharing, mounted machines in both directions, opened iTunes on both machines. On both machines I get this message (see attached). Problem is I can't see where to achieve this. I went to security and turned off the OS Firewall on both boxes, and have no 3rd party FW app. Is there a place to "allow communication on port 3689"?