Airport Extreme loses internet connection
Lately my 27" iMac loses internet/connection to airport extreme. It's still shows it's wirelessly connected to the airport (the wireless icon in the menu bar is on and checkmark next to my router), but as my screenshot shows below, the computer doesn't think it's connected. Doing a speedtest on my iPhone when this happens shows the airport is still working.
27-inch, Mid 2011 iMac
OS X 10.8.3
First Generation Airport Extreme
Airport Utility 7.6.3
Any ideas?
iMac, OS X Mountain Lion (10.8.3)