DLNA Clients / Linux Server - Shows no Data

[dunkelgruen]

Subsonic Server working well for all streaming clients on a Lubuntu Linux Operation System.

But no DLNA client works.

My Samsung TV shows all Data, but play nothing.
The Windows Media Player shows no data.

No Firewall on the Server.
Must i open a port on the Server? Which Port?
Any Hint?

Thanks!