No idea what ‘Serviio’ is. Is it a music player, an operating system? 

Two further questions.

Do you just want to play music that is stored on your desktop machine? If so, following the instructions in this article should help. 

Note that Sonos doesn’t directly support DLNA. It may work, it may not, but they don’t officially support it.

Or are you attempting to use your Sonos devices as PC speaker? You may want to refer to the data here.

I have two extern hdd with 8TB of music, I listen to that music on my desktop but also downstairs in the livingroom with Serviio as a DLNA media streaming server.

I want to play that with my Sonos system, because the sound is then much better, but I don't know how to do that. I hope someoen can help me?