How to fix iPhone 'consuming' mobile data

iOS has a feature that automatically uses a mobile data network (LTE or 3G) when a Wi-Fi connection does not guarantee speed or a weak signal, called Wi-Fi Assist. It is enabled by default. The problem with this feature is that everything is implicitly done in the background of the system, so you have no control over your iPhone's mobile data usage when connected to Wi- Fi signal is weak or too slow.

So when the Wi-Fi connection sometimes fails, your iPhone will automatically replace it with a mobile data connection, so your LTE capacity or phone account will just go away. The confusing is due to this feature.

While the Wi-Fi Assist feature is quite useful because it helps you maintain stability when using the network, it can sometimes make you feel uncomfortable. To turn this off, do the following: Go to Settings (Settings)> Cellular then scroll down and turn off the Wi-Fi Assist option.

From now on the feature will no longer use the underground mobile data network, and connections to stream audio or video, download attachments or large files will not work in some Third party apps to help avoid data overload.