This worked for me...
My Yoga 2 Pro wouldn't download over wireless at more than 2 Mbps. Someone suggested disabling HT Mode in the driver's Advanced tab. This increased downloads to around 20 Mbps. The YP2 is connected to my 2.4 GHz network. It doesn't seem to support my 5Ghz network.
I also noticed that my iPhone 5s was getting about 2 Mbps when connected to my 2.4 GHz network, but 80 Mbps or more when connected to the 5 GHz network.
I checked the settings on my Linksys WRT 1900 AC router. The 2.4 GHz network was set to use "WPA2 Personal". I changed this to "WPA2/WPA Mixed Personal" and now I am getting 60 Mbps from the Y2P, which seems good enough. BTW - my iPhone is still only getting 2 Mbps on the 2.4 GHz network.