Failing to setup split DNS

[YoMamasNerd]

Hi guys,

I've setup blocky to block ads and that works fine.
I'm using blocky on a server in my home and besides blocky there are multiple other machines running on it. I want blocky to resolve a domain (abc.xyz) to a local IP and I can't figure out what I'm doing wrong.
My Routers IP is 192.168.178.1
The IP of my Blocky Server is 192.168.178.100
And the IP of my reverse proxy is 192.168.178.223

customDNS:
  mapping:
    abc.xyz: 192.168.178.223

conditional:
  mapping:
    fritz.box: 192.168.178.1
    abc.xyz: 192.168.178.100

I've set the blocky instance as DNS in my router. Do you have any ideas or suggestions on how to resolve the domain locally?