I'd really recommend brushing up some knowledge on how networks are managed and what DNS does, what DHCP manages and what settings are essential for the good operation of a network.
I really can not understand what you're trying to say or what you've done. I really don't understand what IP-ranges have to do with anything.
Normally your router does the DNS ánd the DHCP services. The DHCP hands out the IP-addresses and DNS does the website-name-to-IP resolving. In a normal situation your router will hand your Raspberry Pi an IP-address from within the set address pool. Only if you have more devices than IP-addresses in the pool (for instance 50 devices while the IP range is only 192.168.178.[0-30]). Normally the IP Pool should be something like 192.168.x.[0-255]. The IP-address that is handed out by the routers DHCP server has to fall within the IP Pool anyway otherwise it would never work either.
First you have to set the Pi-Hole to a static IP. This still has nothing to do with IP-ranges or whatsoever. This is done correctly as I saw in the screenshot below the IP Pool captions. A static IP is something different from telling the DHCP server to use the right DNS-server on the network.
Then you tell the router to use your Pi-Hole DNS Server in the DHCP settings instead of the internal DNS Server on the router. Looking once again at that screenshot you posted (with the IP Pool stuff) it seems to me that your router does not support setting a different DNS Server when using the routers DHCP server. I don't have experience with that router, nor can I see enough of all the different settings pages to make a 100% correct conclusion about this.
I'd really recommend leveraging the Pi-Holes' built-in DHCP server to have the Pi perform this operation instead of the router.