I changed some directives in the virtual hosts by hand, but they suddenly disappeared.

Never edit the vhost file manually. On the next update of the system your changes will be overwritten! Instead put your additional vhost configuration in the Apache Directives field in the ISPConfig Interface. If you want to add something manually to other files, e.g Postfix' local-host-names, you can put your configuration at the end of ... Read more

Some services are shown as “Offline” in the ISPConfig system monitor though they are running on the server.

ISPConfig checks the status of the services on localhost (IP: 127.0.0.1). It may be that some of your services only allow connections to specific IP addresses and not 127.0.0.1 (in Apache this is done with the Listen directive). If you allow connections to localhost the status will be shown correctly in the ISPConfig. Another possibility ... Read more

Where is the ISPConfig 2 logfile?

The ISPConfig log is /home/admispconfig/ispconfig/ispconfig.log. The system logs which command was executed in which line in which script and if the command was successful (Status: INFO) or not (Status: WARNING). If you encounter problems with ISPConfig please have a look into the logfile and see if there are warnings. Also have a look into the ... Read more