How to turn Wi-Fi Assist on and off on my Apple iPhone 6S
With the Wi-Fi Assist feature, your Apple iPhone 6S automatically switches to mobile data when Wi-Fi connectivity is poor. When this feature is on, your phone might use more mobile data than normal, and it will count towards the data usage in your plan.
1. Touch Settings.
2. Touch Mobile Data.
3. Scroll to and touch the Wi-Fi Assist slider to change the setting (e.g., from off to on).
4. Wi-Fi Assist is now on.
Touch the Wi-Fi Assist slider again to turn it off.