iPhone 6s
Turning Wi-Fi Assist on or off
You can set your phone to use mobile data automatically when the connection to the Wi-Fi network is weak. To turn Wi-Fi Assist on or off, you need to turn on mobile data.
Step 1 of 4
Press Settings.
Step 2 of 4
Press Mobile Data.
Step 3 of 4
Press the indicator next to "Wi-Fi Assist" to turn the function on or off.
Step 4 of 4
Press the Home key to return to the home screen.