ISPConfig manages the directories of the sites; you can not change the directory of a site to a folder outside of the website.
I also need to change the document root for my ISPconfig 3.3 with apache I set in apache directives under sites, options - this DocumentRoot /var/www/clients/client2/web3/public I just need to add public as the subdirectory for the Contao cms. How can i verify the new document root directory?
I think it should be always under web like the above sample given by @till. So yours should either be: Code: DocumentRoot {DOCROOT_CLIENT}/public or alternatively: Code: DocumentRoot /var/www/clients/client2/web3/web/public To test it, you can simply create any index file to that public folder and open it in a browser or curl it. There normally should be an index file created by ISPConfig in the web folder for newly created web site which you can also copied to there.