Backend OK, FrontEnd -> redirect errors

Hi there,
Running WP 4.5, OSX 10.11.3, MAMP Pro 3.5, Theme 2012
If I access http://www.4d-consulting.com I get a redirect error.
* removed .htaccess
* deactivated all plugins
* switched theme to 2016
=> same error
I can login to the backend with no problem, http + https.
What else can I do?

Greetings,
Peter