While using Pi-hole as only DNS, nothing is loading

[RamSet]

@LaNouille974

alongside an IPv6 (fe80::1) out of nowhere (I don’t understand…).

That is your IPV6 gateway (your Router).

@LaNouille974

First of all: IPv6 is disable everywhere in my LAN. DHCPv6 on the router is turned off. Pihole IPv6 is disable too (I think. It don’t let me tick any of DNS IPv6 upstream servers).

Not according to the debug log.

You have a GUA IPV6 address enabled/used on your RaspberryPi that does not match the IPV6 IP that was configured during initial setup.

[✓] IPv6 address(es) bound to the eth0 interface:
   fe80::1b9a:168:61ef:879 does not match the IP found in /etc/pihole/setupVars.conf

See

Use IPv6 ULA addresses for Pi-hole

Many users have reported that frequently changing IPv6 addresses cause page load to be slow or even prevent from working at all. The issues can be fixed by updating the IPv6 address in /etc/pihole/setupVars.conf followed by a run of pihole -g. However, this solution turns out to be very inconvenient since it might be necessary to change the IPv6 address on a regular basis (maybe even multiple times a day). An alternative approach we are currently looking into is the usage of ULA addresses which…

in order to get a more stable IPV6 IP address.

On the other hand, it seems that your gateway does not want to respond to pings on both IPV6 and IPV4 IP either.

[i] Default IPv4 gateway: 192.168.1.1
192.168.1.1
   * Pinging 192.168.1.1
192.168.1.1...
[✗] Gateway did not respond. (https://discourse.pi-hole.net/t/why-is-a-default-gateway-important-for-pi-hole/3546)
 
[i] Default IPv6 gateway: fe80::1
fe80::1
   * Pinging fe80::1
fe80::1...
[✗] Gateway did not respond. (https://discourse.pi-hole.net/t/why-is-a-default-gateway-important-for-pi-hole/3546)

@LaNouille974

but alongside an IPv6 (fe80::1) out of nowhere (I don’t understand…).

That's (as seen above) your IPV6 IP of your gateway.

@LaNouille974

DNS server of my LAN (loop ??).

You are right about the loop here but it's a little more tangled than what you think.

According to your config, you are pointing and using Pi-hole with the upstream DNS as the gateway (192.168.1.1).

I don't know how that gateway is set-up or what/how it works when it comes to DNS (remember it doesn't respond to pings, could be that it's not allowing/responding to DNS queries either).

IF your DNS server within the gateway points to 253 then you definitely threw the requests in a loop and the only way it will work is when the request is bounced/tried via the IPV6 DNS server that the router uses.

Between your request and the moment it's tried via the IPV6 resolver (as a fallback at router level), there is a noticeable delay, never the same though. So probably that's why you see the slow response time.

What I recommend doing is setting it up like this:

Pi-hole set up to use a different upstream server (Any of the available there or even a custom one, maybe a local Unbound instance Redirecting... ).

Raspberry Pi set up with ULA IPV6.

Gateway set-up with IPV4 IP of Pi-hole as it's (sole) WAN DNS.

One thing to keep in mind. If the gateway is your DHCP server, then it will propagate via the DHCP packet itself as the default gateway to all clients.
Because of that, Pi-hole will see all the requests originate from the gateway's IP (see logic):

Client1 <--->
Client2 <---> Gateway <--> Pi-Hole
ClientN <--->

If your gateway allows you, you should specify the default DNS server as your Pi-hole IP at DHCP server level (setting).
Otherwise you have 2 options:

1.Disable DHCP within the Router and enable it on Pi-hole.
2. Manually specify the IPV4 IP of Pi-hole on each and every client.

Oh and one more thing:

If IPV4 and IPV6 are both present and enabled within a network, IPV6 is preferred and unless you have your IPV6 settings correct, you might sometimes, see ads (that get resolved via IPV6 and because erroneous settings, bypass Pi-hole).