I have the same issue with S6 edge. I can manually set the time but if I choose "Automatic Date Time" it changes my time zone to Mountain when I'm actually located in the Central Time zone.When I attempt to clear cache by holding Power+VolumeUP+Home, the screen shows "Installing System Update", The update fails. I checked in settings and the last update was 2-1-17 and it can not find a newer update to install from that screen. My wife's S5 is set to "Automatic Date Time" and it works fine. What to do next?