Done and my ProFTPd is now listenning on localhost, but (after proftpd restart):
1. Error message on restart stays
Code:
Shutting down ProFTPD Server: done
Starting ProFTPD Server: - warning: "ProFTPD" address/port (192.168.0.100:21) already in use by "ProFTPD Default Installation"
{my_url}.com - SocketBindTight in effect, ignoring DefaultServer
2. ISPConfig still reports service FTP-Server: Offline
--edited: first line - changed "is not listenning" to "is now listenning" - was my terrible misstake