Adguard as primary DNS - unable to resolve DHCP names

[s4nguine]

Hello everyone,

Recently I moved from OpenWrt to OPNSense and so far it's great! I have only one problem that appeared after redesigning my DNS setup.

Since I have a local domain with PKI set up I need a more advanced DNS setup, and I appreciate functionalities of Adguard I ended up with design like this:

1. My main DNS server is Adguard installed on OPNsense, bound on port 53
2. I have a second BIND server outside of the router that holds my domain records
3. In Adguard I pointed BIND server as an upstream for my domain

It works fine for the most part, the problem is when I want to resolve the name for DHCP assigned devices, from dnslookup I get "server can't find 'host': NXDOMAIN". It's not a firewall issue for sure, I also can't resolve DHCP leases names from the opnsense itself.

I thought that the problem would be solved after I enabled Unbound on the router with the option to register leases, and then pointed to this unbound server in Adguard Private reverse DNS servers but still no luck, same message.

I'm not that experienced when it comes to troubleshooting DNS queries, so I would be really grateful for any help.