Several people that I know who are using the S6 and S6 edge on tmobile are having the same issue. If you click on the data usage how much is showing as Android OS? Mine is using 50-100MB's of data in the background a day. Some days more. I am not able to block the background data unless I root the phone. Over the course of a month this adds up. If it was a normal app I could block or uninstall it. Anyone know how to fix this excess data usage?
Best answer by spezialy
Disabling "Google Settings > Security > Improve harmful app detection" fixed the problem for me.
When I disabled my Android OS went from averaging about 2-5MB an hour to .1 or .2 MB an hour. Looking into this option it appears it is more for google to track usage of apps and less about harmful app detection. Not a problem for people on wifi all day. But very annoying and I hope this helps others save their mobile data.