I followed the HowToForge tutorial which says at step 9 ( https://www.howtoforge.com/tutorial...doveot-and-ispconfig/2/#-install-lets-encrypt ) to install letsencrypt and leave the generation of certificates to ISPConfig. There are checkboxes in the server configuration to activate SSL and Let's Encrypt, but these are always emptied again after returning to the configuration dialogue. Generating certs in the SSL tab doesn't help in this regard. FireFox just complaints about SSL headers that are too large and the SSL and Let's Encrypt checkboxes are emptied again. How is Let's Encrypt supposed to work with ISPConfig 3.1?