uupps, seems I've chosen the wrong forum, because my question belongs to ' AMPPS ' and not to the 'Softaculous Auto Installer '.
Anyway - I've installed phpBB on my local machine by myself using the ' install.php ' and not an Auto Installer.
I get into the issue by calling the startpage of phpBB.
When there is no internet connection, I'm getting the ' 2002 - the local server's socket is not correctly configured '. But by reconnection my local machine to the internet everthing works fine.