CNAME to Tableau Server on AWS

Hi,
I am new to Cloudflare. I am trying to setup a CNAME called reports to Tableau server instance on AWS. It keeps saying Web server is down. But, it works when I got the AWS URL directly.

Error 521 Ray ID: 59771fa84b930d7a • 2020-05-22 14:18:36 UTC

Web server is down

Any ideas what I am doing wrong.

-Rao