I made up a Raspberry Pi 4 running Pi-Hole for a friend's home. His router demands that if you force the ip address for the DNS server (through DHCP), that you MUST specify 2 distinct ip addresses. They cannot be the same ip and neither can be 0.0.0.0. It will not allow just a single DNS server ip address.
I don't really want to build 2 RPis, so I thought I'd try doing a DHCP reservation for both the eth0 interface as well as the wlan0 interface, using consecutive addresses. I'm testing this on my own installation (even though my router doesn't enforce the 2 DNS situation, it will accept a second one).
I haven't seen anything wonky in the past 3 days. Do you think this is a reasonably safe way of working around the router's limitations?