Wi-Fi Assist is a new feature included with the iOS 9 update. It optimizes the hand-off between Wi-Fi and cellular data network.
In the past, when a device leaves the effective range of a Wi-Fi network, it would try to cling onto the Wi-Fi network for as long as it can, even when the Wi-Fi signal became too weak to be effective. The user would have two choices, either turn Wi-Fi off, or wait until the device is completely out of range and switches to cellular data network.
How does Wi-Fi Assist work
Wi-Fi Assist regularly checks your Wi-Fi connection to determine signal strength. If the Wi-Fi signal performance drops, Wi-Fi Assist automatically switches to a cellular data connection until the Wi-Fi signal improves. By doing so, the hand-off between your Wi-Fi and cellular data would be automatic and smooth.
How to turn it ON/OFF
First, update your eligible Apple device to iOS 9. After the update, Wi-Fi Assist is turned on by default. Once enabled, it operates in the background automatically.
You can turn it on/off anytime by follow these steps.
Scroll all the way to the bottom of the page
Turn Wi-Fi Assist ON/OFF
Wi-Fi Assist & cellular data usage
If you are frequently in an area with poor Wi-Fi coverage, the Wi-Fi Assist feature could switch your device from Wi-Fi to cellular data more often to provide the best data network experience. And with increased exposure to the cellular data network, your device could utilize more cellular data usages than before.
For tips on managing data usage on iOS, click here.
iPhone 6s, and iPhone 6s Plus
iPhone 6 and iPhone 6 Plus
iPhone 5c and iPhone 5s
iPad Air (1st and 2nd generation)
iPad (4th generation)
iPad mini with Retina display (2nd generation)
iPad mini (3rd generation)
The following devices can be upgraded to iOS 9, however, Wi-Fi Assist option will not be available
iPad (2nd and 3rd generation)
Wi-Fi Assist does not activate for some third-party apps that might use large amounts of data. For example, apps with audio or video streaming functionality, or email apps with attachments download feature.
If you are data roaming outside of Canada, Wi-Fi Assist would not automatically switch to cellular for data connection.