Configuring DNS Server - LAN or WAN Settings on ASUS Router?

Thanks for the response guys.

So nmap and pihole-FTL both shows only one DNS server and that is the routers address itself, not pi-hole (10.0.0.10). Output attached below.

pi@raspberrypi:~ $ sudo nmap -sU -p67 --script dhcp-discover 10.0.0.1
Starting Nmap 7.70 ( https://nmap.org ) at 2021-01-25 00:42 GMT
Nmap scan report for 10.0.0.1
Host is up (0.00059s latency).

PORT   STATE SERVICE
67/udp open  dhcps
| dhcp-discover:
|   DHCP Message Type: DHCPACK
|   Server Identifier: 10.0.0.1
|   Subnet Mask: 255.255.255.0
|   Broadcast Address: 10.0.0.255
|   Domain Name Server: 10.0.0.1
|   NetBIOS Name Server: 10.0.0.1
|   Domain Name: mydomainname
|_  Router: 10.0.0.1

deHakkelaar - I read your response here. Few questions:

  1. Does this mean I have to flash custom firmware on my router to use pihole? Merlin doen't have a stable version for RT-AX86U yet, only a beta version, So I will have to wait.
  2. Using pi-hole for DHCP - is that recommended?
  3. Where is pihole getting its current queries from?
  4. Should I just let is continue as is, since I don't seem to be seeing any ads on any clients while browsing?
  5. Would changing the DNS setting on the LAN page make any difference?