Ntp not updating system time
Note that the Adafruit GPS Hat uses GPIO 4, physical pin 7, so you would need to change the commands given in this document.
I start by describing how to get the Raspberry Pi running with just a LAN connection - no display, keyboard or mouse - a so-called headless operation.
I then describe how to configure NTP for your environment, and adding a GPS/PPS receiver to convert your box into a stratum-1 NTP server including the operating system updates needed.
There are some helpful Linux commands scattered throughout this page.
These notes are almost as much for my own records for the next time I need to visit this project, but I hope they may be helpful to others.
As an experiment, I purchased one of the low-cost credit-card-size Raspberry Pi computers, and have configured it to run NTP (Network Time Protocol).
I have also used this board with a GPS receiver with pulse per second (PPS) output to make a stratum-1 NTP server, but as I know little of Linux, it has taken some time to achieve this aim!