System time growing an accumulating latency

High Sierra 10.13.6. I have my system clock displaying the hours, minutes and seconds in the upper-right corner of the screen.

I have had this laptop for years and the time has always been 100% accurate (from what I can observe). Meaning: my cell phone and laptop always keep in sync with each other and the minute segment changes at almost the exact same time.

Over the last few weeks, I have noticed an accumulating "lag" in the time as maintained on my laptop. First, I noticed it was about 15 seconds behind my cell phone and the other computers in our house. A few days later I noticed it was 25 - 30 seconds behind. It is now several minutes behind! For instance it might be exactly 9:00 AM EST but my laptop is showing 8:57:43 AM EST, etc.

The main question here is: how can I "resynch" my laptop with the actual time (as maintained by all the "atomic clocks" I hear about, and likely what all devices are synched with)?

Secondary to that, anybody have any ideas as to what could have caused this? Just curious on that one! My disk storage is very full and I keep getting warnings about that, so maybe its impacting the time somehow?! Thanks!

In System Preferences > Date & Time, you should be able to use a Time Server by checking a checkbox and specifying a time server:

Depending on where you live on the globe, the available time servers may be different.