Authelia portal.conf

location / {
  set $upstream_authelia http://192.168.88.3:9091; # AUTHELIA IP:PORT
  proxy_pass $upstream_authelia;
  client_body_buffer_size 128k;

  #Timeout if the real server is dead
  proxy_next_upstream error timeout invalid_header http_500 http_502 http_503;

  # Advanced Proxy Config
  send_timeout 5m;
  proxy_read_timeout 360;
  proxy_send_timeout 360;
  proxy_connect_timeout 360;

  # Basic Proxy Config
  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_set_header X-Forwarded-Host $http_host;
  proxy_set_header X-Forwarded-Uri $request_uri;
  proxy_set_header X-Forwarded-Ssl on;
  proxy_redirect  http://  $scheme://;
  proxy_http_version 1.1;
  proxy_set_header Connection "";
  proxy_cache_bypass $cookie_session;
  proxy_no_cache $cookie_session;
  proxy_buffers 64 256k;

  # If behind reverse proxy, forwards the correct IP, assumes you're using Cloudflare. Adjust IP for your Docker network.
  set_real_ip_from 172.19.0.0/16;
  real_ip_header CF-Connecting-IP;
  real_ip_recursive on;
}