I am trying to configure Pi-Hole on Opnsense V 25.7. When I try to add my pi-hole's IP Address under "services / ISC DHCPv4 / [LAN]", it's not shown in the menu. I had the wizzard configure the DHCP server when I first started it configured it. Any suggestions would be helpful. If you need more information, please let me know.
You want to enter that IP address into the "DNS server" option field of the DHCP subnet? Just enter the address and press ENTER. That's all.