@Jaywalker, Another forum member had this similar issue last year. I am currently running 2x Pi-Holes, on their own VLAN, with static ip reservations on the LAN page (Rick’s method #2). Then in each VLAN (not the Pi-Hole VLAN), I manually set the DNS servers to the static ip addresses of the PI-Hole’s. I would not change the WAN DNS settings as this caused all sorts of issues with connecting.
The only real hitch is that the Pi-Hole’s VLAN needs to have “Inter-VLAN Routing” specifically checked for this to work. This can then be overruled manually through the internal firewall rules, by denying the Pi-Hole’s VLAN network access to the other VLAN’s. If you have a guest network or whatever that does not have “Inter-VLAN Routing” checked, but uses the Pi-Hole for DNS, this should still work.
Your original post may have been correct, when you set the DNS servers manually to those of the Pi-Hole IP’s, did you by chance reboot the router and/or your laptop to reinitialize the connection at the time? Your laptop may not have refreshed the updated DNS. Try setting the Pi-Hole on its own VLAN prior to installing the software or setting it up. Then go through everything as you had previously. That will give it the IP address you want, not within the range of your current DHCP.
Anyway, here is the original post from last September. It has screenshots with my setup. Hope it helps.