I'm having WiFi connection speed problem with new iPad Air and Airport-extreme 802.11ac.
I can get over 30Mbps download speed with old iPad2 but with new iPad Air, I get only 7 or 8Mbps.
I saw https://discussions.apple.com/thread/5516013 (Slow WiFi on the new iPad Air). He solve the problem by changing the Channel Bandwidth settings on the router but not such setting on airport-extreme 802.11ac.
I had same problem. I restored my iPad air and set it up as a new iPad not from my backup. My backup had even original iPad stuff so I was thinking May be that was causing some issues. It solved my problem and I am getting constant speed, even in the basement. Be careful if you decided to restore and set up as a new iPad, make sure to save your pictures and videos etc otherwise you won't be able to retrieve it.
I was using a linksys G router
I'm sorry this was posted twice
iPad Air slow WiFi connection
