If have doubts about settings being pushed by router to clients, try install nmap on Pi-hole:
sudo apt install nmap
And do a dhcp-discovery against the router that does DHCP for your clients with below one:
sudo nmap -sU -p67 --script dhcp-discover <ROUTER_IP_ADDRESS>
Example with 10.0.0.2 doing DHCP for my network:
xbian@avr ~ $ sudo nmap -sU -p67 --script dhcp-discover 10.0.0.2
Starting Nmap 7.40 ( https://nmap.org ) at 2019-02-21 06:31 CET
Nmap scan report for noads.dehakkelaar.nl (10.0.0.2)
Host is up (0.00066s latency).
PORT STATE SERVICE
67/udp open dhcps
| dhcp-discover:
| DHCP Message Type: DHCPACK
| Server Identifier: 10.0.0.2
| Subnet Mask: 255.255.255.0
| Broadcast Address: 10.0.0.255
| Domain Name Server: 10.0.0.2
| Domain Name: dehakkelaar.nl
| Hostname: avr
|_ Router: 10.0.0.1
MAC Address: B8:27:EB:EE:1B:BD (Raspberry Pi Foundation)
Nmap done: 1 IP address (1 host up) scanned in 4.20 seconds