Are you getting a “challenge did not pass” error? Can’t find a matching hostname for your Webmin panel to generate Let’s Encrypt certificates to?
The trick is that Lets Encrypt only works with Apache. Most Webmin/Virtualmin panels are running on miniserv Perl scripts on port 10000. We must follow the following steps:
1. Create a virtual server (or sub server) for the matching domain in Virtualmin.
2. Go to Webmin > Webmin Configuration > SSL Encryption > Let’s Encrypt
3. Request Certificate for “Apache virtual host matching hostname”. Set renewal for 12 months!