Websockets on port 443 - 502 Bad Gateway

Traefik Traefik v2
1

Hey there,

I am desperately trying to get websockets to work on port 443. I cannot use a different port, as 80 and 443 are the only ports not getting blocked by the clients firewall. :-/

But I keep getting a 502 Bad Gateway error.

This is my config:

version: "3.9"  # optional since v1.27.0
services:
  reverse-proxy:
    # The official v2 Traefik docker image
    image: traefik:v2.8
    container_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.traefik.entrypoints=websecure
      - traefik.http.middlewares.sslheader.headers.customrequestheaders.X-Forwarded-Proto=https,wss
      - traefik.http.routers.traefik.middlewares=sslheader@docker
      - traefik.http.routers.traefik.tls=true
      - traefik.http.routers.traefik.rule=Host(`traefik.showroom.local`)
      
  websocket:
    image: node:12.22.2-alpine
    container_name: websocket
    mem_limit: 2G
    working_dir: /home/node/app
    command: sh /home/node/app/run.sh
    expose:
      - 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,wss
      - traefik.http.routers.websocket.middlewares=sslheader@docker
      - traefik.http.routers.websocket.tls=true
      - traefik.http.routers.websocket.rule=Host(`ws.showroom.local`)
      - traefik.http.routers.websocket.entrypoints=websecure

Any idea what is wrong here?