time is off by hours when phone not connected to cellular or wifi network for a day or two?

[anon(10057381)]

when my S7 edge is not connected to wifi or cellular network for a day or two, the time is off by hours.... is this normal?

 

[SpookDroid]

Is it rebooting maybe? If the time is set to AUTOMATIC but it doesn't find a valid network or time information in the network, the phone defaults to whatever it was set to manually, and that might be why yours is 'off'; check your manual time settings.