wordpress 4.1 https redirect loop reverse proxy

So this is driving me nuts, having a costumer with a wordpress shop, using version 3.4.1 for a long time with no issues. Last december they wanted to upgrade to wordpress 4.0. We did what we thought would be a simple upgrade on the test server but got in a world of pain.

Every single request to public pages and admin gets in to redirect loops. I am no server guy and this is hard for me to understand. The server setup is as following described from the server company.

User-> Exteral www server -> datacenter HA-proxy -> internal http server -> testing server

The testing server is running apache.

The server is configured so that all request is forced to go via https. So lets say we try go access http://example.com/style.css the server will show https.

Today we tried again with wordpress 4.1 and a fresh install. After the install no js och css files gets included with https and it is not possible to log in to admin.

Changed siteurl and home variable in database to use https, but still the page wants to include all assets with http. Going to wp-admin results in a redirect loop.

Tried different combinations of http and https for the siteurl and home variable in the wp-options table with defining every possible combination of things in wp-config

define('FORCE_SSL_ADMIN', true);
define('FORCE_SSL_LOGIN', true);

define('WP_HOME','https://example.com');
define('WP_SITEURL','https:///example.com'); 

if ($_SERVER['HTTP_X_FORWARDED_PROTO'] == 'https') $_SERVER['HTTPS']='on';

Does anyone know what to start looking into, can this be solved with code on our side or should the hosting companies look over their setup even more?