DoH on Chromebook

Hi, I’m using a Chromebook running Chrome OS 78.0.3904.92 with chrome://flags/#dns-over-https set to Enabled. I changed the DNS server for my network connection to When I visit, it shows the following:

Connected to Yes
Using DNS over HTTPS (DoH) No
Using DNS over TLS (DoT) No
AS Name Cloudflare
AS Number 13335

Any ideas how to get this to work? Here’s the URL it told me to include in the forum:

Any assistance is much appreciated!