Pi-hole worked, then stopped. Note: as far as I recall, I changed nothing save upstream DNS servers, but it just stopped blocking requests a bit after 1800 yesterday. Curiously, it began to work, kinda, this morning, but still isn't blocking anything from a list of adult sites that I added. Note: my Windows 10 client is using the Pi-hole server as its DNS (10.0.0.18).
Pi-hole is running on a Raspberry Pi.
I selected upstream DNS servers + added the default adlist + porn list.