By default,
Wi-Fi Assist is turned on. You may
disable Wi-Fi Assist if you don't want your iOS device to stay connected to the Internet when your Wi-Fi connection is bad. Go to C
ellular or Mobile Data in the
Settings menu. Then scroll down and hit the
Wi-Fi Assist slider.
Wi-Fi Assist allows you to stay connected to the Internet even if your
Wi-Fi connection is weak. For example, if you're using Safari with a bad Wi-Fi connection and a webpage won't load,
Wi-Fi Assist will kick in and switch to cellular mode, allowing the
webpage to load. Most apps, including Safari, Apple Music, Mail, Maps, and others, support Wi-Fi Assist.