No warning posted on startup
Seen in Tools/Pi-hole diagnosis:
Warning in NTP client:
Standard deviation of time offset is too large, rejecting synchronization
Now, if I ssh to the pi-hole server, and check the time, it looks OK to me:
pi@gob: sntp clockpi
2025-06-01 15:43:55.944734 (-0400) +0.000265 +/- 0.000327 clockpi 10.10.20.253 s2 no-leap
clockpi is the ntp server handed out by my DHCP server.
Pi-Hole takes (by default) 8 measurements of the time from the specified NTP server. If these vary from each other in offset by more than a certain amount, they will be rejected.
Unless you have manually changed the time server to clockpi in Pi-Hole's settings, it will not be used.
Pi-Hole by default uses pool.ntp.org as its time server, rather than the one specified by DHCP. The NTP Pool is a volunteer operated project, and most of the time the servers are reliable, but from time to time a server may provide unreliable data.
Thanks for the super helpful response. I assumed that it was my NTP server because I got two different errors the two times I booted the pihole that the problem was on my end. And now I've found the setting and updated it to use my local NTP server.