When Apple introduced the Control Center feature in iOS 7, it gave users shortcuts to certain iOS features like the WiFi toggle. Users could turn WiFi on or off via this toggle, but with iOS 11, Apple made it so that tapping the WiFi toggle no longer turned it off permanently, and instead only turned it off temporarily where the next day it would be enabled again.
Take note that this permanently turns off your iPhone’s WiFI until you go through those same steps to turn it back on. If you’re on a limited data plan then forgetting to turn back on WiFi could potentially result in your data draining a lot faster. Also note that when not connected to WiFi, there are certain features that you’ll be missing out on. This includes (but is not limited to):
For the most part, your iPhone will continue to function as per normal, and some of these “limitations” when not connected to WiFi aren’t immediately noticeable or might impact you too much, but it could be worth noting all the same. If you think you might forget to turn WiFi back on, then you can turn off WiFi temporarily through the Control Center.
By default, if you temporarily disable WiFi, it will turn itself back on at 5 AM local time. However, we should point out that there are instances in which it can turn back on earlier. According to Apple’s support website, this can occur when you restart your device or if you walk or drive to a new location. For example, if you temporarily disable WiFi because you’re at a cafe and its WiFi isn’t particularly strong, but if you leave the vicinity of the cafe (and nearby networks), it will turn back on again.