Conditional Forwarding Error - UDM SE + Pihole

[ZurkeyDurkey]

Expected Behaviour:

I have a UDM SE acting as my DHCP server, and I currently have pihole acting as my DNS server running on unRAID 7.0.0 as a Docker Container. I'd like to keep the UDM SE as my DHCP server, but would like the pihole to be able to get my device names from the UDM SE. I've tried to research this, and it looks like Conditional Forwarding is what I need working on the pihole.

I have multiple VLANs set on my UDM SE, across different subnets. 192.168.40.1 for Default and Unifi devices, 192.168.50.xx for other devices, 192.168.60.xx for IoT, etc. In the UDM SE, every VLAN has the pihole IP set as the Primary DNS server, with 1.1.1.1 as the Secondary DNS server. In the WAN1 section of the UDM SE, the Primary DNS is 1.1.1.1, and the Secondary is 8.8.8.8.

Additional info:
UDM SE Gateway IP: 192.168.40.1
pihole IP - 192.168.40.2

Actual Behaviour:

It never successfully applied because I think I am entering the format incorrectly, or am missing information. On the pihole DNS Settings, I went to Conditional Forwarding and typed in 192.168.0.0/16. Clicking 'Save & Apply' gave me a dns error (see attachment).

Debug Token:

https://tricorder.pi-hole.net/AXMSocqk/

Any help is appreciated. Still learning this stuff, and it has been a rollercoaster ride.

[Ladrien]

Things have changed with the update to v6, but I believe it should be:
true,192.168.0.0/16,<dhcp server ip>,<local domain name>

[ZurkeyDurkey]

Thanks for the reply and direction on this. I'll give that a shot.

Not to get too far off-topic, but for the local domain name, I would be using whatever is listed in my UDM SE, correct? I saw that pihole and the UDM SE both have domain sections; so I wasn't sure which. If it is the UDM SE, I have a Domain option for each VLAN I created but they are blank.

I do own a domain, so wondering if I can just use that, like, iot.registereddomainname.com and cameras.registereddomainname.com.

Attaching screenshots.