Normally, an app is allowed to use metered data even in the background, when you are not actively using the app in the foreground.
You can individually disallow an app from using metered data in the background (by turning off Background data for the app under Settings > Apps).
Starting in Android 7, to disallow all apps from using metered data in the background, instead of going through each app one by one, you can turn on Data Saver.
LG Phoenix 2 running 7.0: Settings > Data Manager > Menu (3 dots) > Data Saver
LG Xpression Plus running 9.0: Settings > Network & Internet > Data Manager > Menu > Data Saver
Nord N200 running 12.0: Settings > Mobile network > Data usage > Data saving
Then under "Unrestricted data access" (or "Unrestricted apps"), you can see all the apps whether they are excepted from Data Saver. (When an app is excepted from Data Saver, the app is allowed to use metered data in the background even when Data Saver is on).
Usually at least "Google Play services" is excepted. I believe apps like Gmail and (Google) Voice use "Google Play services", so that Gmail and Voice do not need to be excepted, and you can still be notified of new emails or incoming calls, when you are on metered data and not actively using Gmail or Voice in the foreground.
If you have an app that should but does not send out or receive incoming data, when you are on metered data and not actively using the app in the foreground, then have the app excepted from Data Saver (either from the list of all apps such as under "Unrestricted data access", or the individual app under Settings > Apps).
https://source.android.com/docs/core/data/data-saver
https://developer.android.com/traini...ops/data-saver
Bookmarks