I have the same problem with the network drop and horrible speed with my Lenovo Y50. Before I used to enjoy 5GHz and high speed, but now the ping is skyrocketing once or twice a minute, and 2,4Ghz network is 1/3 of the speed I get with 5Ghz, but it's doesn't drop the network that often.
I'm totally ****** on Intel for this network card, because it's horrible and all the drivers they put in doesn't seem to help at all. I try to contact both Lenovo and my webshop for advise, but nobody bothers to answer me. Nice to see that I'm not the only one with this network card and this issue tho.. I would like to demand Intel to give me a new and DIFFERENT network card so I can enjoy my PC in peace.