Ucs-sso reverse proxy problem


yesterday i configured the office 365 connector and it works all fine. the thing is that it is just reachable when you’re in the local network (company) and u cant reach the ucs-sso page outside the company. We have a nginx reverse proxy server and i tried to configure the proxy but iam not an expert about proxies. I have not changed any apache2 configs at the ucs itself and configured this at the nginx server:

upstream xx {
        server xx.xx.local:443;

server {
        listen   80;
        server_name xx.xx.local;
        return 301 https://$host$request_uri;

server {
        listen   443 ssl http2;
        server_name xx.xx.de;

        access_log  /var/log/nginx/xx.access.log;
        error_log  /var/log/nginx/xx.error.log;

        ssl_certificate /etc/letsencrypt/live/xx/fullchain.pem;
        ssl_certificate_key /etc/letsencrypt/live/xxp/rivkey.pem;

        ssl_protocols TLSv1.2 TLSv1.1 TLSv1;
        ssl_prefer_server_ciphers on;
        ssl_dhparam /etc/nginx/ssl/dhparam2048.pem;
        ssl_ecdh_curve secp384r1;
        ssl_session_cache shared:SSL:30m;
        ssl_session_timeout 10m;
        ssl_session_tickets on;
        ssl_session_ticket_key /etc/nginx/ssl/nginx_ticketkey;

        add_header Strict-Transport-Security "max-age=31536000; includeSubDomains; preload";

        location / {

                proxy_pass http://xx.xx.local;

                proxy_next_upstream error timeout invalid_header http_500 http_502 http_503 http_504;

                proxy_set_header        Accept-Encoding   "";
                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;
                add_header              Front-End-Https   on;

                proxy_redirect     off;

i can reach the ucs portal page but cant continue to the ucs-sso page (cannot find the page)