lets encrypt challenge fails

I have installed a fresh virtualmin virtual server on an ec2. I have adjusted the ionos DNS A records to point to ec2 IP. When I request a certificate from lets encrypt (or using certbot in cli) I get

Type: unauthorized Detail: Invalid response from http://${DOMAIN}.well-known/acme-challenge/Mv0tCvDDT73eYW83mgsmA6FtpIH13wq6cVp_WGeZ6xk [2607:f1c0:100f:f000::28c]: 204

When I test in browser, the URL does indeed return a 204 but I would expect nginx to serve up a page with much more information. What am I doing wrong?