We understand that it happens on both your Samsung devices. This makes it look as if it's something else than a device issue. For us to investigate, we'd like some more info. Could you please send over the following?
If the same thing happens on 3G/4G and WiFi
What happens if you try a friend or family members account
If you use a VPN
If you use any cache-clearing or battery saving apps
If you haven't tried yet, you can always see if a quick reinstallation works. Read here how.