If I am connected to wifi at home, sometimes web pages and apps have a hard time loading/connecting. If I turn airplane mode on and re-connect to wifi everything works quickly. It's just a pain to be switching in and out of airplane mode to make and recieve calls.
iPhone 6, iOS 9.2.1
When you turn Airplane Mode on - you disconnect from WiFi. If you turn it off and then on again and that helps the connection, try power cycling your router and force restart your phone.
Unplug the router from power for about 30 seconds, then plug it in again. While you are waiting for the router to be fully ready to go, force restart the phone. To force restart your device, press and hold both the Sleep/Wake and Home buttons for at least ten seconds, until you see the Apple logo.
Why does wifi work better in airplane mode?
