Synology mobile apps won't connect anymore after setting up Traefik reverse proxy

Hi,

I recently switched from Nginx Proxy Manager to Traefikv2.
It's installed on my Ubuntu Server through docker.

I got most of my services running as before, but I can't connect my Synology mobile apps (DS File/Synology Drive) to my Synology Diskstation anymore.
It used to work out of the box on NPM, but I think I'm missing something here.
Before using Traefik I could just connect through the apps by e.g.
nas.mydomain.com:443, but that doesn't work anymore.

Through the webbrowser I can connect just fine, only the apps won't connect.

Could someone maybe give me some help?

Thanks a lot!

Traefik config.yml:

routers:
  ds412:
      entryPoints:
        - "https"
      rule: "Host(`nas.local.mydomain.com`,`nas.mydomain.com`)"
      service: ds412
      middlewares:
        - default-headers
        - authelia
      tls: {}
  synology-drive:
      entryPoints:
        - "https"
      rule: "Host(`drive.local.mydomain.com`,`drive.mydomain.com`)"
      middlewares:
        - default-headers
        - authelia
      tls: {}
      service: synology-drive
  synology-fs:
    entryPoints:
      - "https"
    rule: "Host(`fs.local.mydomain.com`,`fs.mydomain.com`)"
    service: synology-fs
    middlewares:
      - default-headers
      - authelia
    tls: {}

services:
  ds412:
    loadBalancer:
      passHostHeader: true
        servers:
          - url: "http://10.20.15.101:8015"
  synology-drive:
    loadBalancer:
      passHostHeader: true
      servers:
        - url: "http://10.20.15.101:8045"
  synology-fs:
    loadBalancer:
      passHostHeader: true
      servers:
        - url: "http://10.20.15.101:8048"

middlewares:
  authelia:
    forwardAuth:
      address: "http://authelia:9091/api/verify?rd=https://auth.mydomain.com"
    authelia@docker:

  default-headers:
    headers:
      frameDeny: true
      sslRedirect: true
      browserXssFilter: true
      contentTypeNosniff: true
      forceSTSHeader: true
      stsIncludeSubdomains: true
      stsPreload: true
      stsSeconds: 15552000
      customFrameOptionsValue: SAMEORIGIN
      customRequestHeaders:
        X-Forwarded-Proto: https