Surely there is a better way to do that, but this method has worked for me correctly. I take this message to ask developers to add a button for the automatic generation of let'sencrypt SSL certificates, specific for the ispConfig control panel in Tools or System. In my example I assume that the ispConfig server has an FQDN name with subdomain: isp.example.org After entering ispConfig at https://isp.example.org:8080 and accepting the risk that firefox or chrome warns when entering, I have created a subdomain with isp.example.org with SSL and Let's Encrypt. From the console by ssh # cd /usr/local/ispconfig/interface/ssl # mkdir stop # mv ispserver.* stop # ln -s /etc/letsencrypt/live/isp.example.org/chain.pem ispserver.crs # ln -s /etc/letsencrypt/live/isp.example.org/fullchain.pem ispserver.crt # ln -s /etc/letsencrypt/live/isp.example.org/privkey.pem ispserver.key # reboot You may not need to restart the server and it is sufficient to restart apache with: # service apache2 restart But since I had to reboot anyway for a kernel update, I did the reboot. Now, Google searches for an "ssl checker" and check that your server at 8080 port, has a valid Let'sEncrypt ssl, inserting in the form "isp.example.org:8080" The test must be OK. Now you can enter with your browser in the control panel at https://isp.example.org:8080 Note that it is possible for your browser still warn about the wrong certificate. If this happens, clear the browser cache or use another one for now.
Do you know this: https://www.howtoforge.com/tutorial/securing-ispconfig-3-with-a-free-lets-encrypt-ssl-certificate/
No, i'm not. To much tutorials to look for that I write to the top "Surely there is a better way to do that..."