For those still having wifi issues, you may want to try turning off your AirPlay on other iDevices. Extracts from Apple Support Communities <https://discussions.apple.com/>
<https://discussions.apple.com/thread/6546549?start=1005&tstart=0>
leroybrussee Oct 21, 2014 3:16 PM
Re: iOS 8 Wi-Fi problems <https://discussions.apple.com/message/26645046>
Ever since upgrading to IOS 8, including IOS 8.01, 8.02 and 8.1 I had the well known Wifi issue.
wifi speeds dropping from 120mbps to about 2mbps @ 5ghz in within a minute after connecting to the wifinetwork. often i couldn't even surf at all. but the wifi signal was always strong.
With every update i was hoping for a solution from Apple but it never came.
Tried everything that can be found on the internet.
Resetting the network settings.
Disabling "wifi networking" under Settings > Privacy > Location Services > System Services.
Reinstalling my Ipad from scratch
Used different routers and different setups.
Automatic ip's and fixed ip's and different dns servers just to be sure.
Nothing worked. The only workaround is switching to a 2.4Ghz network.
So i was doing some tests and found THE solution, but i don't like it all.
One of the biggest changes in IOS 8 is the ability to use airplay without a network. by using a wifi connection in combination with bluetooth.
And here lies the problem.
I disconnected al my Airplay devices from my network. Denon AV-amplifier AVR2113, Pioneer wireless speaker XW SMA3 and an airport express.
Et voila... My Ipad is back to normal. fast... no very fast internet connection and stable as ****. Just like iOS 7 was.
Working with it for a couple of hours now without any trouble at all.
But do i connect one Airplay device to the network the wifi is not stable anymore and extremely slow again on my ipad air.
My Macbook running mac os x mavericks doesn't have these issues, neither does my iphone 5S. and they are also on the same 5ghz network.
So I can create and recreate the issue and create a work around... Apple please come with a solution that makes me able to use airplay an ipad (on ios8) on a 5ghz network! like in iOS 7!!!!