NGINX to Exchange 2010

Hello,

Really hoping someone can help!
Having issues with autodiscover through nginx. If i manually navigate to the autodiscover URL (https://autodiscover.domain.com/autodiscover/autodiscover.xml) I am prompted for credentials, but all login attempts fail.
Navigating to the autodiscover.xml URL on a different domain on the same CAS but not through nginx also prompts for credentials although login attempts are successful and return the XML.

Exchange 2010

Config:

server {
listen 80;

server_name autodiscover.domain.com;

return 301 https://$host$request_uri;
}

server {

listen 443;
ssl on;
ssl_certificate /linktocerts;
ssl_certificate_key /linotocerts;
server_name autodiscover.domain.com;

proxy_pass_header Date;
proxy_pass_header Server;
proxy_pass_header Authorization;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header Accept-Encoding "";
proxy_pass_request_headers on;
proxy_set_header Host $host;
more_set_input_headers 'Authorization: $http_authorization';
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_http_version 1.1;
proxy_request_buffering off;
proxy_buffering off;
proxy_set_header Connection "Keep-Alive";

location / {
proxy_pass https://mail.eurogarages.com;
proxy_http_version 1.1;
}
# location ~* ^/owa {proxy_pass https://internaladdress;}
# location ~* ^/ecp {proxy_pass https://internaladdress;}
# location ~* ^/rpc {proxy_pass https://internaladdress;}
# location ~* ^/autodiscover {proxy_pass https://internaladdress}
}