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After setting a single client manually, or the DNS setting on the router, DNS will resolve and ads will be blocked.
Either DNS will not work at all and no site can be reached, or sites load with ads.
This is a fresh install of Raspbian and Pi-hole after a bad SD card. When I test on one machine (Windows) by manually setting the DNS server, it will either load pages with ads or not resolve IP at all. I have updated Pi-hole, rebuilt gravity, and rebooted it several times all to no avail.