So there have been times when your iPhone, automatically joins a public WiFi network like when you are in a train station. Chances are that the WiFi connection will not be reliable and at some point your iPhone won’t get any data at all, but it will remain connected to that network. All you have to do if you need internet, is to disable wifi and use your cellular data.
But in the latest beta of iOS 9, Apple just fixed that problem, by making the iPhone capable of choosing when is the right time to switch from WiFi to cellular. That is when it detects that the WiFi is pretty much unusable. Hopefully you have enough data on your plan. If that’s not the case, then you can turn off this feature, and use only WiFi, even if it’s not able to provide you a reliable connection.
The feature is called “WiFi assist” and can be found i settings, under the cellular section
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