Did you read the perfect server for Ubuntu 16.04? https://www.howtoforge.com/tutorial...l-pureftpd-bind-postfix-doveot-and-ispconfig/ I'll cite the text: "Notice: The ISPConfig 3.1 version that is used in this tutorial is currently in beta state. The ISPConfig old stable 3.0.5p9 version can not be used on Ubuntu 16.04 as it is not compatible with PHP 7."
