JSS behind Nginx reverse proxy

We have a Nginx reverse proxy with ssl offloading configured on a seperate host then the jss server with the following configuration:

server {
        listen                  443 ssl;
        server_name             [domain];

        access_log              /var/log/nginx/[domain]/access.log;
        error_log               /var/log/nginx/[domain]/error.log;

        ssl_certificate         /etc/ssl/[domain]/fullchain.pem;
        ssl_certificate_key     /etc/ssl/[domain]/privkey.pem;

        add_header X-Frame-Options "SAMEORIGIN";
        client_max_body_size    128M;

        location / {
                allow [trusted ip];
                deny all;

                proxy_set_header        Host $host;
                proxy_set_header        X-Real-IP $remote_addr;
                proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;
                proxy_set_header        X-Forwarded-Proto $scheme;

                proxy_pass              http://10.30.11.131:8080;
                proxy_connect_timeout       600;
                proxy_send_timeout          600;
                proxy_read_timeout          600;
                send_timeout                600;
                proxy_redirect          http://10.30.11.131:8080 https://[domain];
        }
}

we can connect to the jss server with our browser, login and configure. However when we are trying to connect with the casper admin on mac osx we get a "Connection error while connecting to. .." The traffic seems to stop at the nginx server. The strange part is, starting "Recon" it will connect to the server.. Anybody familiar with this issue ??