We have a Ruby application that uses Time.now in order to get the current time (and sign some requests that are time-sensitive).

Every time that we reboot the droplet (Ubuntu 18.04 LTS) the time returned is completely wrong, but after some seconds (about 20 seconds) the time becomes correct again and then everything works as expected.

The problem is that for some seconds immediately after the reboot the time is wrong.

Why is this happening? How can we solve this? This seems a general issue on all droplets and not something specific to a single machine.