How to install PHP 7.x as PHP-FPM & FastCGI for ISPConfig 3.1 with apt on Debian 8 and 9 available now. PHP 7.1 is the next generation of the PHP programming language, it is up to 2 times faster than PHP 5.6 and 14 times faster than PHP 5.0 according to the release notes. The new PHP version is not 100% compatible with PHP 5.x as some deprecated API’s have been removed.