What might be the reason for this? I had to look up my IP address and configure it manually, so I got it to display as "connected," but there is still no internet when I turn off airport.
Alright, connect the computer via ethernet and then open "Network Utility". (Go to the Applications folder then Utilities) Once it opens select "Ethernet" from the drop down menu under "Select a network interface for information." And then post what it says next to "IP Address".
My mistake. I'm connecting through one of those things that connects modem to power outlet and then other power outlet to computer, and one of them wasnt plugged in. >.<