Both my 27" and my 21" iMacs suffer from wifi issues after sleeping or from cold boot. They say they are connected to the router, but have an exclamation point for lack of internet connection. I have done extensive research and tried some of the fixes like deleting the preferences files for airport from the /Library folder, but the issue still remains on BOTH iMACS. I know this is an issue for many running Mountain Lion (and Lion) with newer iMacs. What have YOU done to solve issues with wifi? I'm about to have to go back to Snow Leopard. EDIT: I wanted to say I have no issues with anything but my iMacs which are 2010 and 2011, both on 10.8. My Macbook on 10.8 (2010), ipads (2 ipad 2's), and iPhone 4s all work properly on this router.