How can I set a public DNS for openwrt and AdGuardHome running on another server for LAN

I currently have AdGuardHome(AGH) running on router serving DNS to all my network.

Over the past month, a couple of times the whole home network went down because of AGH issues (once an update broke it, another time, the logs filled the entire storage of router).
Currently my router also uses the AGH for DNS, hence when AGH is down, router itself don't have any internet access (for things like installing software and such).

I am thinking of having AGH run on my home server on proxmox instead.
I would like this new AGH act as the DNS server for all LAN connections. But have the router use a public DNS like google or cloudflare for its own dns queries. That way, The router can still communicate to the internet if my homeserver is down.

I think this would also help me when I am away from home and the homeserver is down, I can still connect to router via wireguard for any troubleshooting becase I run tailscale on the homeserver for other things.

I am pretty new to all of this.

How can I set up:

  1. Openwrt lan to use a custom ip of new AGH(lets say 192.168.1.55) to serve DNS queries
  2. Openwrt router to still use a public DNS for its own queries
  3. Do I need to set the DNS on each device separately? Or can they all refer to the router 192.168.1.1 for DNS and the router send it all to 192.168.1.55 for resolving? In this case, can AGH know which device is sending the queries or will it just say 192.168.1.1 because its all coming from router.

Appreciate your time and help regarding this.

Don't need the openwrt LAN to use it, but the lan clients.
It's configured in the DHCP.

That's actually the default config (to use the IPs coming from the ISPs DHCP reply), so I guess you must have changed it.

No, unless you want to.

They could, but shouldn't, then you can't use IP based config on the AGH, if there's such a thing.

It'll see the 1.1 IP.

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