reverse proxy with lotus webmail

[testctn]

I'am a newbie and I'm trying to configure nginx as a reverse proxy on 443 to 443 port of an internal domino server but It doesn't work. I can reach the login page and if I use wrong credentials I have an error from domino internal server instead when I use correct credentials the login page is proposed again with no error. My config is

    server {
        listen  443;
        ssl     on;
        ssl_certificate         myserver.pem;
        ssl_certificate_key     myserver.key;
        ssl_session_timeout     5m;

   
        server_name  name.of.external.srv;

        error_log /tmp/error.log debug;

        location / {
            proxy_pass         https://name.of.internal.srv;
            proxy_redirect     off;
            proxy_set_header   Host             $host;
            proxy_set_header   X-Real-IP        $remote_addr;
            proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;

            client_max_body_size       10m;
            client_body_buffer_size    128k;

            proxy_connect_timeout      90;
            proxy_send_timeout         90;
            proxy_read_timeout         90;

            proxy_buffer_size          4k;
            proxy_buffers              4 32k;
            proxy_busy_buffers_size    64k;
            proxy_temp_file_write_size 64k;
        }
    }

Someone can help?