I've been having problems with my wifi being slow and/or disconnecting for me on my iPhone 6 plus since 9/20. I've tried everything possible to fix it and they all seem to be temporary fixes which stop working after a few hours to a day. Called Apple and they want me to exchange my phone in store, the store has no stock though and I don't believe it is a problem with the phone itself since so many other users are complaining about it as well. UPDATE 9/30/2014 I returned my phone at the Apple store for a replacement and it seems to have fixed my problem. I will post back after a few days. UPDATE 10/1/2014 Wifi disconnecting again after setting up as a new phone. Definitely a software issue. UPDATE 10/3/2014 iOS 8.1 beta seems to have fixed the wifi issue. Been connected for a few days now with no noticeable problems. I would recommend restoring to it if you are registered.