2x AdGuard Home: what/where to put IPv4/6 DNS addresses?

I've installed Adguard Home on my Banana R3 (OpenWrt) and in a docker container on my NAS (Asustor AS6704T). It is working but quite often quite slow. My assumption is that I did not state the IP addresses of the 2 AdGuard Home instances correctly for IPv6 on one or more places.
Banana R3 OpenWrt = 192.168.1.1
Docker container on NAS = 192.168.1.25

Current config:

Network - DHCP and DNS - Forward:
192.168.1.1
192.168.1.25
::ffff:c0a8:101
::ffff:c0a8:119

System - Interfaces - wan:
192.168.1.1
192.168.1.25
::ffff:c0a8:101
::ffff:c0a8:119

System - Interfaces - lan - Advanced Settings:
192.168.1.1
192.168.1.25
::ffff:c0a8:101
::ffff:c0a8:119

System - Interfaces - lan - DHCP Server - Advanced Settings - DHCP Options:
3,192.168.1.1
6,192.168.1.1,192.168.1.25

System - Interfaces - lan - DHCP Server - IPv6 Settings:
2001:1c03:4d04:dc00::1
fd35:c317:11a6::1

Is there something I can correct/improve?
What am I supposed to state as IPv6 DNS servers for 192.168.1.1 and 192.168.1.25?
Do I have to give some IPv6 DHCP options?
Should DNS serves explicitly be stated in lan interface?

Thanks in advance for your help.