Try it with Samsung's own server and see if that's it.
Many have reported issues with all these servers so without that small detail I can't look at this. But now that you know it matters, be sure to ask the network server's maker about their support of smart tvs.
We use our Samsung (UE46D7000) to stream video files off our network server. It all works fine but one movie (unfortunately Alvin & The Chipmunks so its the first file in the list) is now duplicate about a hundred time. There are pages and pages of copies so its a real pain to browse to the other files we want.
We deleted that movie from the server and also checked for hidden copies - nothing there anymore. Still, SmartHub gives us hundreds of copies which of course are not playable.
I've tried finding ways to clear the file list cache, including factory resetting the TV and the SmartHub. No change.
Any ideas how to fix this?