i do need some help regarding Docker traefiks and nodeJS backend:

My Proxy settings with HTTPS and serving my frontend on port 5000 works fine. But for some reason i dont get my backend http routes working:

That is how backend config looks like:

services:
   backend:
      image: node:latest
      container_name: nodejs-backend
      command: node /usr/src/app/index.js
      volumes:
         - ./dist:/usr/src/app
         - ./img:/usr/src/app/img
      networks:
         - default
         - web
      labels:
         - traefik.enable=true
         - traefik.http.routers.backend.rule=Host(`backend.herzsprechen-app.de`) || (Host(`backend.herzsprechen-app.de`) && Path(`/registerNewPlayer`)) # some more routes
         - traefik.http.routers.backend.tls=true
         - traefik.http.routers.backend.tls.certresolver=lets-encrypt
         - traefik.http.services.backend.loadbalancer.server.port=8080
networks:
   web:
      external: true

If i start the backend like so, i can hit the /login route. But nothing more than that works.
So below are my routes:

module.exports = class HttpRoutesConfiguration {

    constructor(app) {

        const storage = multer.diskStorage({
            destination: (reg, file, cb) => {
            cb(null, 'img')    // for prod '/usr/src/app/img'
            },
            filename: (reg, file, cb) => {
                cb(null, Date.now() + path.extname(file.originalname))
            }
        })

        const upload = multer({ storage: storage });

        app.use("/img", express.static('/img'));     //serve static img files
       
        app.post('/registerNewPlayer', upload.single("avatarPicture"),  playerController.registerNewPlayer);
    
        app.post('/login', bodyParser.json(), playerController.loginUser);

        app.post('/addPlayer', upload.single("avatarPicture"), playerController.addPlayer);

        app.post('/deleteUser', bodyParser.json(), playerController.deleteUser);
    }
}

and for testing purpose my cors config allow origin : ‘*’. I just want that every route after backend.my-domain.de/… hits the corresponding backend.

Here no route is working

– Host(backend.my-domain.de) && PathPrefix(/registerNewPlayer)

Here /login works. /registerNewPLayer returns 500 internal server error

– Host(backend.my-domain.de)

/login works. /registerNewPLayer returns 500 internal server error

Host(backend.hmy-domain.de) && ( PathPrefix(/login) || PathPrefix(/registerNewPlayer) )

/login works

Host(backend.my-domain.de) && (PathPrefix(/login))

/login works ; /registerNewPlayer doesnt work

Host(backend.my-domain.de) || (Host(backend.my-domain.de) && Path(/registerNewPlayer))