Forgetting the wifi network then re-connecting solved the issue for me.
Didn't know about the reset network settings. Trying it out now.
Having the same issues on my iPad Air. I'll try reseting network settings.
Are you sure it's wifi of just data in general.
My wifi is noticeably slower but so is 3G too.
Yes, Same here on iPhone 5S and iPad 4. Waiting until work tomorrow to test their Wi-Fi to see if its the same. If it is then iOS 8 bug.