I just got a new Galaxy S5 and am having trouble with email. If I'm connected to wifi, email accounts work fine. If I'm not connected to wifi, I get nothing for either my gmail or Microsoft exchange email accounts. Sometimes I get an error message about inability to connect to the network (even though icons indicate connection to 4G) and sometimes not. My sync settings are all good to go and I spent an hour at the AT&T store today with no luck. Please help!