Custom DNS records on Local DNS not resolving

mageeagle

I installed Nextcloud on my LAN, and it's only accessible locally. I didn't set up a VPN. I set up PiHole's custom DNS records to point to the IP of Nextcloud, e.g. nc.local. It worked a for quite a while, but it stopped working a few weeks ago, possibly due to updating GrapheneOS. I tried accessing normal websites on the phone and it shows up on PiHole's query log, but none of the .local domains I setup gets through to PiHole. Any clues on how I could maybe add conditions on not blocking certain hostnames? Or maybe it's another issue?

thmf

mageeagle You could start diagnosing with essential tools like nslookup or dig to see if the host is resolvable from other devices in your LAN, then from your phone. May need to install a terminal app for this, like the built-in Terminal (Debian VM on your phone), or ConnectBot (easier) from github and connect it to "local".
Things to start from:
nslookup nc.local
nslookup nc.local pihole_IP
... and see what it says.

mageeagle

All my other devices can connect to nc.local as well as other names with .local, but the phone with GrapheneOS.

While running nslookup (on my computer), I did find out that the IPv6 is used as default and fails to resolve, might be due to how I setup my PiHole. But it works when I manually enter the IPv4 address of PiHole when running nslookup.

I'll try and fix PiHole's network configuration to make it work with IPv6 when I have more time and come back with results.

But I still find it weird that it used to work on my GrapheneOS device but stopped working after a month or so. The DNS servers on the GrapheneOS network settings shows both IPv4 and IPv6 addresses of PiHole, so technically it should resolve by reaching the IPv4 server even it didn't manage to reach the IPv6 DNS server?

n3t_admin

mageeagle

mageeagle should resolve by reaching the IPv4 server even it didn't manage to reach the IPv6 DNS server?

No, it will get an NXDOMAIN (or whatever the response is) for the AAAA record and fail the lookup. I don't know exactly why IPv6 gets prio in this case, but that is the usual behavior. Unless you need IPv6, you might turn it off altogether on PiHole, so that it only resolves IPv4. That should fix the issue.

mageeagle

n3t_admin I turned off IPv6 on PiHole, but my router apparently still advertises its IPv6 address... There is no setting on the router to turn off IPv6 as it comes from the ISP...

thmf

mageeagle Check if you can disable DHCP v6 on your router. This way the router will stop assigning v6 addresses in your LAN.
Note, DHCP v4 must stay on or your devices won't get the "usual" v4 address.
And don't disable IP v6 on router's WAN interface as it may break the router-ISP connectivity.

mageeagle I turned off IPv6 on PiHole

What you currently see in pihole interface -> system -> tools -> interfaces -> your LAN interface? Is it "2 addresses connected to interface" with inet6 being "fe80"? Or is it something different?