If you are trying to use CleanBrowsing on Comcast Xfinity and it doesn’t seem to be working, the reason might be their Protected Browsing option that prevents any other DNS from working, except their own.
To fix that, go to: https://internet.xfinity.com/network/protected-browsing
And toggle the Protected Browsing to off.
Once changed, wait a few minutes and it should start working. You won’t lose any protection as all our DNS filters also block access to malicious and malware domains.