Just did some experiments with following settings:
proxy_set_header X-Real-IP $remote_addr;
proxy_pass_header X-Accel-Redirect;

No change:( ...its time to give up or any ides?

Also tried:
proxy_cache_bypass $cookie_nocache $arg_nocache $arg_comment;
proxy_cache_bypass $http_pragma $http_authorization;

proxy_set_header X-Real-IP $remote_addr;
proxy_pass_header X-Accel-Redirect;

#proxy_pass_request_headers off;
#proxy_pass http://localhost:9000;
#proxy_pass_request_body off;
#proxy_redirect off;
proxy_buffering on;
}
}