Authelia-Swag with Plex in host mode -> Error 502

[Jorman]

Hi all, I have a problem with authelia-swag and docker, I think it will be a very long post, I am not an expert in reverse-proxy, please bear with me
Let’s start with the configuration:

• I use a DDNS with https://dynv6.com/ where I have configured the following fields in my Zones
  
  
• On the router, I forwarded ports 81 and 444 to the respective ports 80 and 443 on my server
• Then I downloaded and installed the authelia-swag docker and this is the configuration docker

networks:
  net:
    driver: 'bridge'

services:
  swag:
    container_name: 'swag'
    image: 'lscr.io/linuxserver/swag'
    restart: 'unless-stopped'
    networks:
      net:
        aliases: []
    ports:
      - '81:80'
      - '444:443'
    volumes:
      - '${DOCKER_APPDATA}/autelia-swag/swag:/config'
      - '${DOCKER_APPDATA}/autelia-swag/swag/log/letsencrypt:/var/log/letsencrypt'
      ## Uncomment the line below if you want to use the Authelia configuration snippets.
      #- '${PWD}/data/nginx/snippets:/snippets'
    environment:
      PUID: '${PUID}'
      PGID: '${PGID}'
      TZ: '${TZ}'
      URL: 'MYDOMAIN.dynv6.net'
      SUBDOMAINS: 'www,whoami,auth,organizr'
      VALIDATION: 'http'
      CERTPROVIDER: 'zerossl'
      ONLY_SUBDOMAINS: 'false'
      STAGING: 'true'
      EMAIL: '***@gmail.com'
    cap_add:
      - 'NET_ADMIN'
  authelia:
    container_name: 'authelia'
    image: 'authelia/authelia'
    restart: 'unless-stopped'
    networks:
      net:
        aliases: []
    expose:
      - 9091
    volumes:
      - '${DOCKER_APPDATA}/autelia-swag/authelia/config:/config'
    environment:
      TZ: '${TZ}'
  organizr:
    container_name: 'organizr'
    image: 'organizr/organizr'
    restart: 'unless-stopped'
    networks:
      net:
        aliases: []
    expose:
      - 81
    volumes:
      - '${DOCKER_APPDATA}/autelia-swag/organizr/config:/config'
    environment:
      PUID: '${PUID}'
      PGID: '${PGID}'
      TZ: '${TZ}'
  whoami:
    container_name: 'whoami'
    image: 'traefik/whoami'
    restart: 'unless-stopped'
    command:
      - --port=2001
    networks:
      net:
        aliases: []
    expose:
      - 81
    environment:
      TZ: '${TZ}'

So I started configuring everything, it took me days but now, for example, Sonarr, Bazarr, etc., work via remote access, so something small I managed to do
However, I can’t get Plex to work! I would like to access it remotely since the plex site is blocked at work, so I can watch Plex on a monitor rather than on a cell phone during my lunch break.
I tried this configuration:

## Version 2024/07/16
# make sure that your plex container is named plex
# make sure that your dns has a cname set for plex
# if plex is running in bridge mode and the container is named "plex", the below config should work as is
# if not, replace the line "set $upstream_app plex;" with "set $upstream_app <containername>;"
# or "set $upstream_app <HOSTIP>;" for host mode, HOSTIP being the IP address of plex
# in plex server settings, under network, fill in "Custom server access URLs" with your domain (ie. "https://plex.MYDOMAIN.dynv6.net:443")

server {
    listen 443 ssl;
    listen [::]:443 ssl;

    server_name plex.*;

    include /config/nginx/ssl.conf;

    client_max_body_size 0;
    proxy_redirect off;
    proxy_buffering off;

    # enable for ldap auth (requires ldap-location.conf in the location block)
    #include /config/nginx/ldap-server.conf;

    # enable for Authelia (requires authelia-location.conf in the location block)
    include /config/nginx/authelia-server.conf;

    # enable for Authentik (requires authentik-location.conf in the location block)
    #include /config/nginx/authentik-server.conf;

    location / {
        # enable the next two lines for http auth
        #auth_basic "Restricted";
        #auth_basic_user_file /config/nginx/.htpasswd;

        # enable for ldap auth (requires ldap-server.conf in the server block)
        #include /config/nginx/ldap-location.conf;

        # enable for Authelia (requires authelia-server.conf in the server block)
        include /config/nginx/authelia-location.conf;

        # enable for Authentik (requires authentik-server.conf in the server block)
        #include /config/nginx/authentik-location.conf;

        include /config/nginx/proxy.conf;
        include /config/nginx/resolver.conf;
        set $upstream_app MYDOMAIN.dynv6.net;
        set $upstream_port 32400;
        set $upstream_proto http;
        proxy_pass $upstream_proto://$upstream_app:$upstream_port;

        proxy_set_header X-Plex-Client-Identifier $http_x_plex_client_identifier;
        proxy_set_header X-Plex-Device $http_x_plex_device;
        proxy_set_header X-Plex-Device-Name $http_x_plex_device_name;
        proxy_set_header X-Plex-Platform $http_x_plex_platform;
        proxy_set_header X-Plex-Platform-Version $http_x_plex_platform_version;
        proxy_set_header X-Plex-Product $http_x_plex_product;
        proxy_set_header X-Plex-Token $http_x_plex_token;
        proxy_set_header X-Plex-Version $http_x_plex_version;
        proxy_set_header X-Plex-Nocache $http_x_plex_nocache;
        proxy_set_header X-Plex-Provides $http_x_plex_provides;
        proxy_set_header X-Plex-Device-Vendor $http_x_plex_device_vendor;
        proxy_set_header X-Plex-Model $http_x_plex_model;
    }
}

And I set up Plex like this

Custom server access URLs
https://plex.MYDOMAIN.dynv6.net:443

But I don’t know if I need to enable Relay, I tried enabling it but nothing changes
Every time I made a change to the Authelia-Swag configuration file, I restarted the docker, while URL changes in Plex were made without a server restart

How can I understand or provide you with more data/logs to understand where the problem is?
I don’t think I can do it without help

Thank you