I'm spending my day trying to set up My Airport to solve my NAT problem. I've searched all over the web and watched YouTube instructions, read many posted directions, but when I get to the port mapping in Airport Utility, I've attempted to add a port in the recommended ranges 49000-65000 or something like that, and don't know what I'm doing. I'm on a iMac G5 Intel Core Duo 2.66MHz, running Leopard, using Airport Extreme Base Station (that's my router, right?). I have ADHD, so speak slowly, with lots diagrams.
If you can explain this to me, I will be very grateful.