Symptom
The base station issues IP addresses to wireless clients through DHCP and NAT, but these clients cannot access the Internet. When a computer is directly connected to the Comcast or Rogers cable modem, the computer is able to access the Internet.
Solution
AirPort Base Station Update 3.84 corrects potential issues with the AirPort Base Station (Graphite) when connected to Comcast or Rogers cable modems and services. You only need this update if you have Comcast or Rogers service and have not been able to connect with your AirPort Base Station (Graphite). See software download document 120107, "
AirPort Graphite Base Station Update 3.84: Information and Download".