DoH and DoT
FireFox
Setting up DOH
Menu -> Preferences -> Scroll down to Network Setting... -> Scroll down and tick 'Enable DNS over HTTPS' and enter in a Custom provider
Checking your browser
Firefox: in your URL bar, type: about:networking#dns
Checking the server with curl
Note: curl version 7.62.0 or above is required.
curl --doh-url https://doh-server https://website
This will download the webpage but would have used the DOH server to resolve the DNS.