I upgraded to iOS 8 on my iPhone 5s as soon as it came out. I started to enjoy the brand new features of iOS 8, only to find out a slow Wi-Fi connection on my iPhone 5s. Sometimes I even couldn't get any Wi-Fi, making me frustrated.
When I searched the Apple forum, I found many users were suffering the same iOS 8 WiFi issues. "Why am I having Wi-Fi problems since I upgraded to iOS 8?" "iPhone 6 WiFi problems." "Why does iOS 8.0.2 not resolve the issue of Wi-Fi connectivity with iOS 8?" In order to solve this, I have searched for tons of information and finally got some tricks on how to fix iOS 8 Wi-Fi problems on iPhone SE/6/6 Plus, and iPhone 5s/5c/5/4s, iPad 4/3/2, iPad mini 2/mini, iPad Air, iPod touch 5th generation. Of course these are just short-term solutions. If you are really tired of this iOS 8 Wi-Fi problems, or other iOS 8 bugs, like blue screen of death, iOS 8 running slow, and etc., you can choose to downgrade iOS 8 to iOS 7.x.
5 useful methods are provided below to solve iOS 8 network problems, including unable to connect to a Wi-Fi network, sluggish Wi-Fi after iOS 8 upgrade and iOS 8 Wi-Fi connection dropping.
Resetting network settings dumps all settings, caches, DHCP info, and any other settings or custom data. It can fix most networking related issues. To do this, just open the Settings app and navigate to Settings > General > Reset and tap on Reset Network Settings.
If resetting network settings doesn't work, you can try to disable Wi-Fi networking. Go to Settings > Privacy > Location Services > System Services, then turn off Wi-Fi networking. This doesn't actually turn off Wi-Fi, but only voids using nearby Wi-Fi networks to assist GPS in determining your location more quickly and accurately.
Setup custom DNS in iOS 8 to fix slow Wi-Fi connection also helps. Here is how you can change your DNS settings: open Settings app and tap on Wi-Fi menu. Find out your Wi-Fi connection from the list of available networks, and tap on "i" button on the right. Scroll down until you see the DNS section, and tap on the numbers to the right. You can enter the new DNS server (Google DNS, and OpenDNS ) address. Then tap on Wi-Fi to go back.
Or, you can try to change Wi-Fi broadcast on your home routers from an N network to a G network, or from 2.4GHz to 5GHz, which depends on your individual router hardware. Some users say it works for iOS 8 Wi-Fi bugs.
If none of the above-mentioned 4 tips have helped, then you can try restoring your iOS device to factory settings to see if it helps. Before you doing that, just be sure to backup iPhone, iPad, or iPod to computer or to iTunes library. To restore your iOS 8 device, you connect your device to the computer. Select your iPhone, iPad or iPod touch when it appears in iTunes. Click on the Restore button in the Summary tab. Then a window will pop up to make sure if you want to restore your device to factory settings. Click on Restore button.
If you find another solution to iOS 8/9.3 Wi-Fi issues, you are appreciated to let us know in the comments!