So I set up an Apache Webserver. Apache is handling the requests and guides them to the web framework flask. And i bought a domain and configured it with an A Record to my Server Ip. And now whenever i enter www.mydomain.com it works but entering mydomain.com(wihout www) gets me to my site, but in the top browser window the server IP shows (for ex. 82.213.123.122)
The Apache 000-default.conf file is
<VirtualHost *:80>
ServerName www.mydomain.de
ServerAlias mydomain.de
WSGIScriptAlias / /var/www/flask/flask.wsgi
<Directory /var/www/flask>
Order allow,deny
Allow from all
</Directory>
ErrorLog ${APACHE_LOG_DIR}/error.log
CustomLog ${APACHE_LOG_DIR}/error.log combined
</VirtualHost>