How to install PHP 7.1, 7.2 and 5.6 as PHP-FPM & FastCGI for ISPConfig 3 on Debian 9
This post is from 2018. Versions, commands and links in it may be outdated. The current release is ISPConfig 3.3.2p1.
There is a new tutorial on installing multiple PHP versions on Debian 9 available. Read more...