Wrong address setup by webinstall

After installing latest oc server on a webhosted site it is impossible to reach the oc page.

My site (let us call it mysite) is hosted on hosteurope,
I installed oc by executing the webinstall. Database and admin user have been successfuly created.
When trying to reach http://mysite/owncloud/ I get redirected to http://ssl.webpack.de/owncloud/index.php/login
the first part of the link makes somehow sense (it is is used for the ssl access to the page) but it misses the name of my site. I tried to reach ssl.webpack.de/mysite/owncloud/index.php/login
directly but it also returns an unable to connect error. (I removed the http from this link since as anew user I am not allowed to post more than two links in my message)

At the moment my .htaccess file is:

RewriteEngine On
RewriteCond %{REMOTE_ADDR} !^10\.30\.7\.1(?:37|38|39|40)$
RewriteRule ^ https://ssl.webpack.de/%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

I also tried without the .htaccess, same error.

The hotline at Hosteurope was not very helpful...

Any clue?