doktornotor pointed to the method how to set it up with HAproxy whenthereisn'tawebserveronport80* HOWEVER: The default nginx Webconfigurator, will also listen on port 80 when the "WebGUI redirect" is unchecked (System -> Advanced -> Admin Access) Then, under the certificate under the Services -> ACME, select/edit/create the certificate, you select the webroot local, and then use /usr/local/www/.well-known/acme-challenge/ (See attachment) I suspect when I check that WebGUI redirect disable, then you could use the "standalone HTTP server" option…  

There were some issues with that code path. Update the package to 0.1.7 or later when it shows up and it should work.