Letsencrypt certificate fails acme challenge


I have a subdomain (monitor.mydomain.com) A record pointed to a server in Digital Ocean running Virtualmin. I successfully created a virtualserver, “DNS domain” is not enabled so I keep DNS management externally. Everything works ok except that when I try to install a Letsencrypt certificate, it fails the acme challenge.
mydomain.com DNS are managed externally (1&1)
I would appreciate your help.


Are you sure your subdomain resolve to correct folder inside your droplet?

virtualserver name should be monitor.mydomain.com or you have to add a server alias to vhost conf file