I have noticed lately that the time on my cell phone (Moto G4) is off by about 20 seconds; specifically it lags the real time so that the minute changes over about 20 seconds after the real minute change. By “real” I mean the atomic time on the Internet, which is also reflected on my laptop and tablet, which get their time from the Internet time servers.
I can tell that the incorrect time it’s getting is from the cell phone service, which I presume is Sprint. If I put my phone in airplane mode but turn on WiFi, and restart it, the time is correct, but as soon as I enable the cellular radio (turn off airplane mode), the time “jumps back” 20 seconds.
Most of the time this is not a very big deal, but it does cause some problems, most specifically with Google Authenticator. Because the 2-factor authentication codes that it provides are time-sensitive, I sometimes get the wrong code. Usually I have to wait until the minute changes (the code changes right then, too), and very rapidly enter the new code into the authentication dialog. You have to be quick.
So why would the cellular network be off by that much on the time? By the way, this is in the Roanoke, VA, area.