How to disable DNS query forwarding?

[MarceloRedfield]

Right now I have in my network my router and a RPi running Pihole + Unbound which is my DNS resolver.
I believe I have disabled all router DNS forwarding settings, but it still keeps port 53 open (no 853) and any queries sent to the router are then forwarded and resolved by the RPi. While not a big deal, a few not-so-well-behaved devices on my network attempt to use the router as its DNS server. While queries are ultimately filtered and responded by the RPi, I wanted to ultimately have the router stop forwarding queries by disabling the appropriate setting instead of a more drastic measure like closing it's port or something like that. I feel like I'm missing something stupid but I can't find what setting I need to disable. DNS Director is disabled.

Any chance someone could lend me a hand? Thanks in advance!

Router: RT-AX88U
FW: 388.1
Router: 192.168.1.1
RPi: 192.168.1.2

pi@raspberrypi:~ $ nmap 192.168.1.1
Starting Nmap 7.80 ( https://nmap.org ) at 2023-02-20 11:46 CST
Nmap scan report for AsusRouter (192.168.1.1)
Host is up (0.00064s latency).
Not shown: 993 closed ports
PORT STATE SERVICE
21/tcp open ftp
22/tcp open ssh
53/tcp open domain
80/tcp open http
139/tcp open netbios-ssn
445/tcp open microsoft-ds
8200/tcp open trivnet1

 

[ColinTaylor]

You can't block traffic destined for the router using Network Services Filter. That's only for traffic sent to the WAN interface.

There's no option in the GUI to disable the router's DNS server. IIRC you can do it by using a custom config file (dnsmasq.conf.add) and setting port=0.

Custom config files

Third party firmware for Asus routers (newer codebase) - RMerl/asuswrt-merlin.ng

github.com

Man page of DNSMASQ

 

[MarceloRedfield]

Perfect, that did the trick.

I was aware the Network Services Filter was for WAN only, but just added here in the rare instance that could be related to the forwards (I know, unlikely, and seems silly now thinking of it).

Thank you so much for the help!