The original post: /r/pihole by /u/whistlingturtle on 2024-11-04 17:34:04.

I apologize for the long story. I tried to write a “TL;DR” but couldn’t formulate something that would have been useful without repeating all the same details.

Currently, I have two problems. They are most probably related. I could say that I don’t know how I ended up in this situation but, technically, that would be wrong, since I wrote everything down along the way.

A few weeks ago, I installed Pi-hole on a Minix computer (running Debian 12) to start experimenting with it. That went very well at first; everything was working as expected, and I discovered queries that I had not previously suspected, coming from various devices on the network.

Then, Pi-hole got into some sort of a mood, where it replied “N/A” to everything. Re-starting its DNS service didn’t help; only rebooting the computer did. And it did it again a few hours later. I searched on Reddit and on pi-hole.net and I found a few posts that seemed to match my case but none of them mentioned a resolution. I wrote about this in a Reddit post but it received no replies, so I eventually uninstalled Pi-hole. (I later found instructions for disabling Pi-hole without uninstalling it.)

Then I installed Pi-hole on my main computer (running Linux Mint 21.2). Yes, I know: Linux Mint is not “supported” by Pi-Hole, but there are people who use it anyway and there doesn’t seem to be a reason why it wouldn’t work. For me, it would be more desirable to use it as the Pi-hole host, because I never shut it down; only reboot it once a month. (Normally.)

After a while, but before I had really started using Pi-hole (i.e. it was covering only the “localhost”), it also got into a mood, similar to what had happened on the Minix, except this time the replies were all “Refused” instead of “N/A”. I didn’t reboot. Instead, I disabled Pi-hole and stopped the FTL service.

While I was still debating whether I should continue trying to make Pi-hole work on my main computer or go back to the Minix instead, I proceeded to change both of their network connections to use a static IP address, as a preparation for whatever I would decide next. For the record, I attributed 192.168.0.198 to the main computer and 192.168.0.196 to the Minix, as well as 192.168.0.197 to another client. (The router is at 192.168.0.1.) This is where my current problems start.

But first I must explain one particularity of my network: my main router is a strictly wired one; an old D-Link, which doesn’t allow me to see, let alone alter, DHCP assignments by MAC address. (But this has never been a problem so far.) I have a TP-Link Wi-Fi router that I bought six months ago and it is set to “Access Point” mode only, with its DHCP service disabled, and it is connected to the wired router like any other client. My network has always been set up this way (for a variety of reasons), i.e. this TP-Link simply replaced an older Toto-Link that I was using in the same manner since 2009. I’m mentioning all this because, currently, anything I connect by Wi-Fi still works fine, including access to a DNS service, because I set the Wi-Fi router’s DNS to 1.1.1.2.

The biggest problem is that, unless I re-start pihole-FTL, anything hardwired to the D-Link wired router (except the Wi-Fi router) is now cut off from any DNS service, even though it is still set to use 1.1.1.2, not 192.168.0.198. I also tried with its default of 0.0.0.0 and that made no difference. I also rebooted it, even though this router is very good at applying changes, i.e. triggering a DHCP release / renew.

So, it appears that, just because Pi-hole is installed on it, this computer insists on using Pi-hole, without seeing that the FTL service is stopped. (After all, it’s not the router that is pointing it back to itself for DNS fulfillment.) Is that really what is happening? It would contradict this claim (from the Post-Install page of the Getting Started section of the doc):

“Pi-hole will not be used by the host automatically after installation.”

Anyway…

Will I have to uninstall Pi-hole to rectify the present situation?

And why is the (hardwired) Minix computer not getting its DNS need fulfilled at all, even after I re-started the FTL service on the other one? Why isn’t it getting it from the external DNS service (i.e. 1.1.1.2) via the wired router as before? All I did was to make it use a static IP. (But I also set it back to dynamic as a test and it’s still not getting any DNS.)