Why would a network port capable 100Mbps not be able to handle a 52Mbps stream?
I am pretty sure that the issue is related to the processing of the server and not the network capability of the tv.
I say this because I also tried playing the content from another client (a NUC with openPHT embedded) and there I can monitor the playback information. CPU usage, bitrate, temp etc.
Only after a coupe of seconds into the movie, the processor activity immediately skyrockets to 100% and the image starts stuttering.
So it looks to me that it is not direct playing the content but the NAS is probably decoding or something (even though the playback information does state it is playing directly).