Chromecast - No Device Found - Airport Solution if using Macbook Pro
Ok, so I could get chrome cast working on my macbook, but I my girlfriends macbook pro just said 'No device found'.
After trawling the web I picked up a lead that it might have something to do with the range the Wifi was running on. The Airport Extreme that i have broadcasts on both the 2.4ghz range and the 5ghz range. It was possible that my macbook was on the 2.4ghz range and didn't have an issue and my girlfriends macbook pro was on the airport extreme 5ghz range.
From what I read, you can't stop the Airport Extreme broadcasting on the 5ghz range but you can get it to give the 5ghz range a different name. Meaning when you select your wifi network you will see two versions of the same network just with slightly different names.
I have a Macbook Pro so I can only advice on how to do this on a Macbook Pro OSX.
Open Finder Window
Open Airport Utility
Click on the capsule and click edit from the popup menu
Click Wireless (from the menue bar on the top of the pop up screen)
Click Wireless Options (at the bottom of the pop up)
Check the "5ghz Network Name"
Call it what ever you want or leave it as the default option.
Probably best to give the computer a restart, check you are on the correct network (You should see the two verisons in the wifi menu) you want to be on the 2.4ghz network, not the new 5ghz network you just created a new name for.
And that is it. Solved it for me. Let me know if it works for you.