The Media Server can be fine-tuned by uisng its own web interface on port 9000, http://WDMyCloud:9000 for example.
It can, but WD advice is that the Twonky UI is for information only, and not to be used for changing the behaviour of Twonky:
http://support.wdc.com/KnowledgeBase/answer.aspx?ID=3299
That’s because WD doesn’t ‘play nicely’ with Twonky. But it can be overcome:
DLNA does tend to ‘chatter’, to see what devices are present on the network.