There is no CMOS battery to keep time in the box, much like all other boxes. They usually synchronized the time when the box connects to a router that itself synchronized time with internet time.

For you case, if you are using mobile hotspot then consult the device manual. If connected to router, normally default time sync settings is already good. So do check its settings. Quite possibly, the router may not be even synchronized as well with internet time.

You can try. Funny enough, my Automatic Date & time setting is Off in Android 7.1.2, and it has no issues with time and date.