2. Disable WiFi Service Settings
This is another fix that you can use on your iOS 8 device or any other iOS device to fix WiFi connectivity issue on iPhone 6.
Go to Settings on your iPhone.
Then, go to Privacy and select Location Services.
Scroll down and select System Services and then find WiFi Networking option.
Flip the switch to disable to WiFi Networking setting.
This won’t turn off wireless networking in iOS. It is recommended you reboot your iOS device after you complete the above steps. Once you phone is rebooted, then try and join the network again to see if the iPhone 6 WiFi connectivity issue is fixed or not.
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