v6 - ntp.sync.server

Help
1

hey all,

I am using my router as my NTP server I have been trying to utilize it as my “ntp.sync.server” (all settings > network time sync).

I have created a host record for my router and added it as my ntp.sync.server but notice that after I save, restart pihole-FTL service & run "pihole-FTL --config ntp” after some time, it seems to get overwritten back to the default option “pool.ntp.org”.

because my router is intercepting NTP requests, when the Pihole tries to hit ‘pool.ntp.org’ directly, inevitably I am getting the error msg in logs:

No valid NTP replies received, check server and network connectivity

curious if anyone else has seen this & knows how that server info is getting managed / how to stop the overwrite. Thanks!

2

Please upload a debug log and post just the token URL that is generated after the log is uploaded by running the following command from the Pi-hole host terminal:

pihole -d

or if you run your Pi-hole as a Docker container:

docker exec -it <pihole-container-name-or-id> pihole -d

where you substitute <pihole-container-name-or-id> as required.

3

before I upload anything, would you be able to provide what I might look for in the log?

I can see the DHCP option providing the router as the ntp-server. in the .toml:

[dns]
 hosts = [
       “<router IP, hostname>”
     ] ### CHANGED, default = []

[ntp.ipv4]
       active = false ### CHANGED, default = true
       address = “”
     [ntp.ipv6]
       active = false ### CHANGED, default = true
       address = “”
     [ntp.sync]
       active = true
       server = “<router hostname>" ### CHANGED, default = “pool.ntp.org”
       interval = 3600
       count = 8
       [ntp.sync.rtc]
         set = false
         device = “”
         utc = true

[tail of FTL.log]

   2025-04-29 EDT [14750/T14751] WARNING: Warning NTP client: No valid NTP replies received, check server and network connectivity
   2025-04-29 EDT [14750/T14751] INFO: Local time is too inaccurate, retrying in 600 seconds before launching NTP server


from the cli:

$ pihole-FTL --config ntp
ntp.ipv4.active = true
ntp.ipv4.address = 
ntp.ipv6.active = true
ntp.ipv6.address = 
ntp.sync.active = true
ntp.sync.server = pool.ntp.org
ntp.sync.interval = 3600
ntp.sync.count = 8
ntp.sync.rtc.set = false
ntp.sync.rtc.device = 
ntp.sync.rtc.utc = true
4

any thoughts on my last reply?

5

Look for potential causes of NTP traffic being blocked, intercepted or re-routed, and/or resolution of pool.ntp.org yielding correct results.
And since you try to use your router NTP server, does your router support that?

6

my router does support acting as an NTP server and also allows you to configure it to intercept NTP requests on the LAN. I was hoping by setting the pihole’s NTP server to my router DNS name things would work seamlessly.

as a test I ran netcat -u 123 to my router and the test succeeded so doesn’t seem like its getting blocked/dropped.

from the pi I can also ping the router via the hostname entry I specified in the pihole’s local DNS records.

7

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