Not working with my DLNA device :(

I’ve bought today a Venztech APLAY One Wifi-speaker, that supports DLNA:

However, when I try to use SWYH, my device is not listed.
I can see SWYH in the app of the device, but nothing happens when I hit play.
Does anybody has any ideas how to solve this?
It’d be great to stream my PC’s audio to this speaker via WiFi.