Websocket over websecure -> ERROR 404

Traefik Traefik v2
1

Hey there,

I am trying to get websockets to run on my setup. But right now it just returns a 404.
I am using a simple nodejs websocket server and React for the webfrontend. However, if react tries to communicate with the websocket server, it just returns a 404.

If I define a different port (e.g. 8081) it works. However I have to use port 443 in order to run this on the infrastructure of my client.

This is my docker-compose.yml

version: "3.9"  # optional since v1.27.0
services:
  reverse-proxy:
    # The official v2 Traefik docker image
    image: traefik:v2.4
    container_name: ${COMPOSE_PROJECT_NAME}_traefik
    # Enables the web UI and tells Traefik to listen to docker
    command: 
      - "--api.insecure=true" 
      - "--providers.docker"
      - "--providers.file.directory=/etc/traefik/dynamic_conf/"
      - "--entrypoints.web.address=:80"
      - "--entrypoints.websecure.address=:443"
    ports:
      # The HTTP port
      - "80:80"
      - "443:443"
      # The Web UI (enabled by --api.insecure=true)
      - "8000:8080"
    volumes:
      # So that Traefik can listen to the Docker events
      - /var/run/docker.sock:/var/run/docker.sock
      - ../setup/ssl:/tools/certs
      - ../setup/traefik/certs-traefik.yml:/etc/traefik/dynamic_conf/conf.yml
    networks:
      vpcbr:
        ipv4_address: 10.5.0.2
    labels:
      - traefik.http.routers.traefik=true
      - traefik.http.routers.api.entrypoints=websecure
      - traefik.http.middlewares.sslheader.headers.customrequestheaders.X-Forwarded-Proto=https
      - traefik.http.routers.${COMPOSE_PROJECT_NAME}_traefik.tls=true
      - traefik.http.routers.${COMPOSE_PROJECT_NAME}_traefik.rule=Host(`traefik.showroom.local`)
 react:
    image: nginx:1.20.1-alpine
    hostname: react
    container_name: ${COMPOSE_PROJECT_NAME}_react
    volumes:
      - ../apps/react/dist:/usr/share/nginx/html
      - ../setup/nginx/default.conf:/etc/nginx/conf.d/default.conf
    networks:
      vpcbr:
        ipv4_address: 10.5.0.5
    labels:
      - traefik.http.routers.${COMPOSE_PROJECT_NAME}_react.tls=true
      - traefik.http.routers.${COMPOSE_PROJECT_NAME}_react.entrypoints=websecure
      - traefik.http.routers.${COMPOSE_PROJECT_NAME}_react.rule=Host(`www.showroom.local`,`showroom.local`)

  websocket:
    image: node:12.22.2-alpine
    container_name: ${COMPOSE_PROJECT_NAME}_ws
    mem_limit: 2G
    working_dir: /home/node/app
    command: sh /home/node/app/run.sh
    #ports:
    #  - 8081:8081
    volumes:
      - ../apps/ws:/home/node/app
      - ../setup/ssl:/home/node/app/ssl
    networks:
      vpcbr:
        ipv4_address: 10.5.0.6
    labels:
      - traefik.http.middlewares.sslheader.headers.customrequestheaders.X-Forwarded-Proto=https
      - traefik.http.routers.${COMPOSE_PROJECT_NAME}_ws.tls=true
      - traefik.http.routers.${COMPOSE_PROJECT_NAME}_ws.rule=Host(`ws.showroom.local`)      

networks:
  vpcbr:
    driver: bridge
    ipam:
     config:
       - subnet: 10.5.0.0/16
         gateway: 10.5.0.1

Any idea what's wrong?