PiHole ran successfully for about 24 Hrs, then stopped. As far as I can see it's fallen back to the router's (FreshTomato) DNS 2 (1.1.1.1). Replacing DNS 2 with 0.0.0.0 stops all traffic and doesn't force the use of DNS 1.
DNS 1 points to the RasberryPi address, on which I'm running PiHole: 191.168.1.38
I've seen suggested in other similar reports, to run on the PiHole machine (Raspberrypi) and the client machine (Linux laptop):
There should be no DNS2 that leads to a DNS server other than Pi-hole. With this DNS server available, the clients are free to use it and some of the DNS traffic will bypass Pi-hole.
Your debug log shows that when Pi-hole tested DNS resolution for a known blocked domain, it was unable to reach the Pi on the outward-facing IP. This indicates a connectivity problem with the Pi on that IP on port 53.
*** [ DIAGNOSING ]: Name resolution (IPv4) using a random blocked domain and a known ad-serving domain
[✓] www.mathenea.com is 0.0.0.0 via localhost (127.0.0.1)
[✗] Failed to resolve www.mathenea.com via Pi-hole (192.168.1.38)
This DNS query does not appear to have gone to Pi-hole, but to the loopback address on that Linux client. The query went to whatever DNS server you have specified for that client, which is not Pi-hole.
I have no DNSs set on the Linux network settings. Don't clients make DNS requests to my Freshtomato router and the router then pass it on to PiHole?
DNS1 on the router is set to that of the Raspberrypi (192.168.1.38). If I set DNS2 to 0.0.0.0 it kills the network and I have to manually power cycle the router to get the network back up and then set DNS2 to a valid address (1.1.1.1)
As you may probably have gathered, I'm very unfamiliar to networking and only have the vaguest concepts!
" Using Your Existing Router For Network-wide Ad Blocking You might not need to use Pi-hole’s DHCP server: In many home environments, your router also functions as your DHCP server. In this case, you can often set Pi-hole to be the DNS server for your network clients in the router’s DHCP (or LAN) settings page, which allows all of your network clients to block ads simply by connecting to the network. Setting it up this way is also what makes Pi-hole very powerful for network-wide ad blocking. W…"
I appreciate the above and it's what I aimed for on my router - DNS1 points to the PiHole LAN address..
I'm going to reconfigure PiHole (<pihole -r>) and see it it helps.
I'm getting pretty discouraged and if reconfiguring doesn't work I'm ditching PiHole and going back to using the built-in Adblock on my router. It's a shame because I like the principle of PiHole on a Raspberrypi and also the handy web monitoring page.