NTP questions

Help
1

Hello Pi-Hole-Team,

I am using Pi-hole version 6.4.2, in which the settings interface has evidently changed.

Unfortunately, I cannot find anything regarding "Network Time Sync settings (ntp)," the ntp.sync.server, or the ntp.sync.interval on any of the settings pages.

I also received the following error message, which persists.

No valid NTP replies received, check server and network connectivity

I then executed the following command in the terminal, to which the terminal responded with a simple "0".

sudo pihole-FTL --config ntp.sync.interval 0

Since then, the following warning has been added as well.

Failed to adjust time during NTP sync: Insufficient permissions

I hope someone can help me out with this.

Regards Matze

2

Settings > System > flip "Basic" into "Expert" > All settings > Network Time Sync

Whats output for below three?

sudo pihole-FTL --config ntp.sync.

dig $(sudo pihole-FTL --config ntp.sync.server)

pihole-FTL ntp $(sudo pihole-FTL --config ntp.sync.server)

Why?
Leave that one on OOTB default 3600 seconds!

From the docs:

Allowed values are: A positive integer value in seconds

3

Thank you , I have now found the setting and disabled ntp.ipv4.active, ntp.ipv6.active, and ntp.sync.active, and set ntp.sync.interval back to 3600.

Then I executed the 4 lines and received the following output.

icke@PiHole-pve:~# pihole-FTL --config ntp.sync.active
false
icke@PiHole-pve:~# pihole-FTL --config ntp.sync.server
pool.ntp.org
icke@PiHole-pve:~# dig $(sudo pihole-FTL --config ntp.sync.server)

; <<>> DiG 9.20.23-1~deb13u1-Debian <<>> pool.ntp.org
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 34842
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;pool.ntp.org.                  IN      A

;; ANSWER SECTION:
pool.ntp.org.           51      IN      A       82.165.178.31
pool.ntp.org.           51      IN      A       148.251.235.164
pool.ntp.org.           51      IN      A       91.98.156.7
pool.ntp.org.           51      IN      A       85.214.83.151

;; Query time: 561 msec
;; SERVER: 192.168.178.17#53(192.168.178.17) (UDP)
;; WHEN: Sat May 23 17:39:35 UTC 2026
;; MSG SIZE  rcvd: 105

icke@PiHole-pve:~# pihole-FTL ntp $(sudo pihole-FTL --config ntp.sync.server)
Using NTP server: pool.ntp.org
........
Received 8/8 valid NTP replies from pool.ntp.org
NTP time offset: -1.065527e+00 ms (excluded 1 outliers)
NTP round-trip delay: 2.286966e+01 ms (excluded 1 outliers)

Now I just have to wait until it is scheduled to run again to see if the messages reappear.

4

Looks all good to me.
Do you still have issues?

5

Not for the time being; I'll wait and see if these errors or warnings reappear, or if any further messages come up.

6

Is above SERVER ip that of Pi-hole?
I dont recommend that.

7

What do you advise against? Posting the IP address here (I had already changed it earlier), or should I make any other general changes?

8

No I meant dont use the own Pi-hole IP for DNS on the host thats running Pi-hole.
These ones:

$ grep nameserver /etc/resolv.conf
nameserver 10.0.0.2
nameserver 10.0.0.4

Configure your router IP for DNS if it doesnt close a DNS loop, or your ISP provided DNS servers, or external ones like Cloudflare, Google, Quad9 etc.

If something goes wrong with the pihole-FTL daemon like during an upgrade or when tweaking, all processes on the host loose DNS resolution which complicates diagnosing.
You wont be able to run the Pi-hole debuger (pihole -d) or reconfigure/repair (pihole -r) without hacking resolv.conf.

9

Thanks for the tip! Hopefully, I’ll be able to look into this in more detail—and at my leisure—sometime next week, once the hardware arrives. I’ll be rebuilding my entire network anyway, as I’m migrating a good portion of it to UniFi and will be restructuring all my IP address ranges in the process.