However I noticed initially I had some probs with movies not streaming from my Twonky server. Let's chat about my setup and what I did to get it working.
My setup includes a Twonky Server 7.2 running on my Lenovo ix4-300d NAS. Most of my media is in m4v, x264 and aac/dts passthrough files. the PS4 media player does not show support for DTS so a lot of my media comes up as 'Cannot play the media' error.
My solution is to have Twonky transcode the movie so it won't be sending a DTS audio signal but hopefully a stereo AAC feed. In my NAS's Twonky Configuration screens, I went into Sharing > Media Receivers.
Then find your PS4's IP address in the list. Twonky for me chose PS3 as it's profile to use however the PS3 is a bit limited in DLNA streaming it seems.
Hmm, I wonder what would happen if I used the generic: Sony Bravia profile?
It seems by using this profile, I can now play all of the media I previously could not. I believe my Twonky server ends up transcoding my stream but I'm not able to verify this via any of the RPC commands for Twonky. Nonehtheless, give this a try and let me know if this works for you too! :)