13 hours ago, jason938 said:
Can anyone explain me how they work together? Personally, when I'm at home, I activate WIFI and disable Mobile Data and when I'm heading outside, I disable wifi and enable mobile data, but for my mom this procedure will be too much and I was thinking to enable them both for her. What I'm wondering - will she have Internet all the time? How they work together? If she comes home and they are both activated home will give priority to WIFI and it will use it instead of mobile data even if it's enabled? Or it will still use Mobile data or...?
Keep both enabled and it'll switch to WiFi when available and use mobile data in all other cases. Not sure on iPhone but on Android go into the network settings (as a precaution) and disable WiFi scanning and, if it's an option, disable to automatically connect to open hotspots. That way only the trusted ones will be connected. Battery drain is negligible, honestly, when both are enabled unless your battery is terrible to begin with. She'll have Internet all the time, assuming she has a data plan, when using either WiFi or the mobile network.