I just replaced my router, and I think I got all the settings to match my old onto the new, including the static IP, and DNS pointer.
Some things I noticed.... The new router's default DHCP range started > x.x.x.100 where the old one started at x.x.x.2 I changed that to match the old. BUT, my pihole static IP was lower than that, initially.
All my pihole logs now look like everything is coming from my router. I can't tell if all ads are getting blocked, but when I try to go to what I think is a known bad actor, I don't get any sort of indicator from pihole. Just refreshes the page into a search page.
I have read so many good things here that I think could be the problem, but I don't want to make tweaks that I can't unchange. I can work my way around the command line, but I am not well versed. So, what I think may work is resetting to initial configuration, but I don't remember all the settings I originally changed, so I don't want to simply reinstate DHCP without removing any static references. But, I think going back to a DHCP assignment, then making whatever assignment the router gives it permanent may do the trick.
A common mistake allot of the fresh hackers make is mistakenly assigning Pi-Hole's IP address to their modem/routers upstream DNS resolving path.
Depending on router/modem, this setting is often called:
WAN settings (not to be mistaken by WLAN setings);
Internet settings;
DHCP client (not to be mistaken with DHCP server);
or "upstream" DNS something.
You dont need to touch these setting ... leave it as is.
If you have not customized allot of settings on the modem/router, its pretty safe to restore the modem to factory default settings.
All you have to do is find the DHCP server section on the router/modem and tell it to hand out Pi-Hole's IP address to the clients as being a DNS server for resolving names to IP addresses.
Have a look at below thread where it turned out the router wasn't able to do this: