Ntp

My GPS-disciplined time server dropped off the network and I didn’t find out for 24 days. The cause wasn’t the hardware, and it wasn’t what I assumed twice along the way — it was a permanent DNS record aimed at an address the router was free to hand to somebody else.

How a Raspberry Pi 5, a cheap u-blox GPS module, and chrony turned into a home stratum-1 time server — the wiring mistakes, the serial-port gotcha nobody documents, and the PPS upgrade that took accuracy from ±50ms to ±350ns.