Greetings!
I feel like this is a stupid problem, but as I am a newbie I hope you will be forgiving :)
My server has as hostname "hostname.de". I installed Virtualmin an created a new Virtualhost named "hostname.de".
In the Webmin/Server/Apache area, I see now two entries:
Default Server Address: Any Post: Any Server Name: Automatic Document Root: Automatic URL: http://hostname.de
Virtual Server Address: xxx.xxx.xxx.xxx Post: 80 Server Name: hostname.de Document Root: /home/hostname.de/public_html URL: http://hostname.de
When I open the url, the index page is opened, but no php is executed.
I tested around and installed wordpress through Virtualadmin into /wordpress and there, PHP is executed.
If there is more information I should provide, please tell me so.