Apple has finally brought in the “obvious” solution to the problem of phones latching on to Wi-Fi even when the connection sucks.
The latest beta of iOS 9 includes a feature called Wi-Fi Assist. It’s designed to deal with the way iPhones currently default to connecting to a Wi-Fi network (and stick with that connection) no matter how weak the signal is. That can be particularly frustrating as the first you realise what’s up is when the signal is so weak that internet-dependent apps effectively become unworkable.
Wi-Fi Assist will automatically switch to a cellular data signal when the Wi-Fi signal is poor. It’s not yet known whether this will be triggered by a specific signal threshold, or if the phone will compare the Wi-Fi strength with the available 3G/4G signal. (The latter option might prove a bit of a battery drain however.) In the current implementation, there’s no option to set a minimum acceptable Wi-Fi strength.
Fortunately Apple has thought about people who don’t want to use cellular data unexpectedly. There’ll be a visual warning of the switch, with the Wi-Fi symbol greying out a little bit in advance. There’s also an option to turn the feature on or off completely.