Router can't resolve DNS [Fixed]

[CB7]

-EDIT-
Problem found. "Allowed clients" under "Access settings" in Settings -> DNS Settings did not have 127.0.0.1 and ::1 included. So if you wish to make use of the access control settings using the allow list, then make sure to include them (alongside the (internal) IP-ranges you wish to whitelist) when running AdGuardHome on your ASUS (Merlin) device.
Also, beware: if you only whitelist your internal IPv4 ranges, then devices running only IPv6 or are attempting to resolve DNS over AdGuard's IPv6-address will not get a response. This can cause delays if it first tries the IPv6 address, times out and then moves on to IPv4. So don't forget to whitelist your IPv6 prefix.


Original post:

I'm having some trouble with my AX3000 running Merlin. For some reason, it appears the router cannot resolve DNS requests anymore. No matter which query you throw at it, it simply says "can't resolve". This means I cannot use amtm either as its incapable of connecting to the entware servers.

What I've tried to do:
- Change DNS settings for WAN
- Append server=8.8.8.8 to /jffs/configs/dnsmasq.conf.add and restarted dnsmasq to try and bootstrap it
- Reboot the router
- Disable DNS Director, just in case
- Modify resolv.conf, but that's not actually possible apparently.

I *can* resolve DNS when I append a nameserver (including the routers local IP, which runs AdGuard):

cbr@TUF-AX3000_V2-F2D8:/tmp/home/root# nslookup snbforums.com
Server: 127.0.0.1
Address 1: 127.0.0.1 localhost.localdomain

nslookup: can't resolve 'snbforums.com'

cbr@TUF-AX3000_V2-F2D8:/tmp/home/root# nslookup snbforums.com 192.168.1.1
Server: 192.168.1.1
Address 1: 192.168.1.1 TUF-AX3000_V2-F9N1.lan

Name: snbforums.com
Address 1: 45.77.76.174 45.77.76.174.vultrusercontent.com

So its perfectly capable of querying DNS servers, but something is wrong causing it not to resolve anything on 127.0.0.1 which is in resolv.conf.
The problem should likely lie with dnsmasq, but it starts just fine and I see it running in the processlist fine as well. Yet, no response.

Any clues as to what could be going wrong here? Without local DNS resolution and no ability to change resolv.conf: I'm stuck. I figured maybe if I install unbound it'll start working, but since I cannot resolve entware: amtm is not doing anything.

 

[ColinTaylor]

Check what (if anything) is listening on local port 53:

netstat -nlp | grep :53

 

[CB7]

Check what (if anything) is listening on local port 53:

netstat -nlp | grep :53

Yes, AdGuardHome is listening on port 53. (And does respond to queries when querying on 192.168.1.1, but not on 127.0.0.1)

 

[ColinTaylor]

Yes, AdGuardHome is listening on port 53. (And does respond to queries when querying on 192.168.1.1, but not on 127.0.0.1)

Please post the complete output from the command I provided. This sounds like an AdGuardHome issue.

 

[CaptainSTX]

I'm having some trouble with my AX3000 running Merlin. For some reason, it appears the router cannot resolve DNS requests anymore. No matter which query you throw at it, it simply says "can't resolve". This means I cannot use amtm either as its incapable of connecting to the entware servers.

What I've tried to do:
- Change DNS settings for WAN
- Append server=8.8.8.8 to /jffs/configs/dnsmasq.conf.add and restarted dnsmasq to try and bootstrap it
- Reboot the router
- Disable DNS Director, just in case
- Modify resolv.conf, but that's not actually possible apparently.

I *can* resolve DNS when I append a nameserver (including the routers local IP, which runs AdGuard):


So its perfectly capable of querying DNS servers, but something is wrong causing it not to resolve anything on 127.0.0.1 which is in resolv.conf.
The problem should likely lie with dnsmasq, but it starts just fine and I see it running in the processlist fine as well. Yet, no response.

Any clues as to what could be going wrong here? Without local DNS resolution and no ability to change resolv.conf: I'm stuck. I figured maybe if I install unbound it'll start working, but since I cannot resolve entware: amtm is not doing anything.

Try disabling DNS Privacy protocol at least while trying to resolve the issue.

 

[CB7]

Please post the complete output from the command I provided. This sounds like an AdGuardHome issue.

tcp        0      0 :::53                   :::*                    LISTEN      7703/AdGuardHome
udp        0      0 0.0.0.0:5353            0.0.0.0:*                           4038/avahi-daemon: 
udp        0      0 :::53                   :::*                                7703/AdGuardHome

 

[CB7]

Try disabling DNS Privacy protocol at least while trying to resolve the issue.

DNS Privacy Protocol is set to "None", I assume that means its disabled

 

[CaptainSTX]

DNS Privacy Protocol is set to "None", I assume that means its disabled

Correct. DNS privacy isn't your problem.

 

[CB7]

Please post the complete output from the command I provided. This sounds like an AdGuardHome issue.

I found the problem! Will also update initial post in case someone Google's this (like I tried doing) and runs in to the same issue.

In Settings -> DNS Settings, if you start working with the "Allowed clients" list under "Access settings": make sure to include 127.0.0.1 and ::1.