I've reinstalled Windows 7 Pro x64 multiple times. Tried pretty much every driver from Intel and Lenovo. Lenovo even replaced the motherboard and wifi antennae, along with replacing the wifi card. Nothing helps.
The AC 7260 is just a piece of crap. It shouldn't be this hard to get a brand new, state of the art wifi adapter working correctly. Intel needs to fix its sh*t.
I guess a lack of competition from AMD in recent years has made them complacent, and now they're releasing junk.