Since this night, pihole cannot resolve any Domain.
I checked the 3 logs and found this in /var/log/pihole/FTL.log :
2025-03-02 12:12:12.150 INFO Tried to resolve PTR "108.3.168.192.in-addr.arpa" on 127.0.0.1#53 (UDP)
2025-03-02 12:12:45.491 ERROR Cannot receive UDP DNS reply: Timeout - no response from upstream DNS server
2025-03-02 12:12:45.491 INFO Tried to resolve PTR "12.3.168.192.in-addr.arpa" on 127.0.0.1#53 (UDP)
2025-03-02 12:13:20.271 ERROR Cannot receive UDP DNS reply: Timeout - no response from upstream DNS server
2025-03-02 12:13:20.271 INFO Tried to resolve PTR "1.0.0.127.in-addr.arpa" on 127.0.0.1#53 (UDP)
I tested different upstream servers which can be selected within pihole-gui, but no change
I was also experiencing this issue and here is how I resolved it for my own setup. First, what we need to realize is that when the PTR IP is printed out, it's printed in reverse. IE: 108.3.168.192.in-addr.arpa = 192.168.3.108 (which tells us the problem is likely with internal private internet space addresses somewhere.
My problem was in the PiHole / Settings / DNS / Conditional Formatting zone I did not account for VLAN address space and put true,192.168.0.0**/24**,192.168.0.1,localdomain
Once I set this to true,192.168.0.0**/16**,192.168.0.1,localdomain the issues for me went away now that I was including 192.168.10 , 192.168.30, 192.168.90 etc
This may not help or solve everyone of these, but it helped me.
