SOLVED: Umlaut

[Ice]

I have found a solution, after long research and many tests.
Docker-compose.yaml looks now like that:

version: '3.5'
services:
  jellyfin:
    image: linuxserver/jellyfin
    container_name: ICE-JELLYFIN
    hostname: ICE
    network_mode: 'bridge'
    ports:
      - 8095:8095
    volumes:
      - D:\Applications\Jellyfin\config:/config
      - D:\Applications\Jellyfin\cache:/cache
      - D:\Daten/Video:/mnt/media
      - media2:/mnt/media2
      - media3:/mnt/media3
    restart: 'unless-stopped'
volumes:
  media2:
    driver_opts:
      type: nfs
      o: "addr=192.168.1.54,ro"
      device: ":/data/Videos"
  media3:
    driver_opts:
      type: cifs
      o: "username=<username>,password=<password>,iocharset=utf8"
      device: "//192.168.1.55/video"

The solution is the added ",iiocharset=utf8" BUT to take this effect you have to recreate the volumes in docker-desktop.
Important: In Docker desktop, you need to delete the container AND any associated volumes. Running the docker-compose up -d command will recreate everything.

media is an example to include a host local folder with media.
media2 is an example to include a shared folder on a nas configured with nfs-access.
media3 imcludes a cifs share on annother nas (on this share/volume the problem occured).