Wi-Fi Assist is a new feature on iOS 9 (the software which ‘powers’ iPhones and iPads).
If you have upgraded your iPhone to iOS 9 or have elected to purchase a new iPhone, then automatically a new feature called Wi-Fi Assist will have been enabled.
Wi-Fi Assist basically works like this: imagine you’re using your iPhone at a coffee shop or your home, and you step outside for some reason and your Wi-Fi signal drops precipitously, perhaps to the point of uselessness. Wi-Fi Assist will then allow your mobile data to kick in so you don’t lose your connection.
This means if your wifi signal is not very strong then the phone will start using the mobile data signal instead, without a change in the symbols letting you know this.
We would recommend turning Off Wi-Fi Assist. The steps are as follows…
First, open “Settings” and then tap “Mobile Data” (Cellular will appear in the USA).
In the Mobile Data settings, you can see how much data you’ve used so far in the current period as well as turn off any apps that you might not want using your mobile data connection. This is obviously a pretty good way to limit mobile data usage from the get-go.
Scroll all the way to the bottom of the Mobile Data settings and turn off Wi-Fi Assist. It will be the last option beneath everything else.
