Yosemite from its first release up until now( latest public beta installed) has refused to work with any channel above 48 for ac wifi. It connects but then the connection slows down to a crawl ( monitoring link speed by pressing alt+click on wifi icon). Recently i installed windows 7 from bootcamp ( am on Macbook pro 11,1 by the way). Same thing happens with windows though. Is this some kind of hardware limitation? For it to happen with 2 different operating systems it points there. Or maybe its a driver problem since both the driver for windows and osx is supplied by apple? Before anyone asks ac wifi works with lower channels up to 48 but the link speed is not good. Router is a Netgear R7000 by the way. What the hell is Apple doing? Filed a bug with them as well. Nothing. I guess they are busy implementing emoticons 