Hello AntJone, if the problem only happens with some of the file, it could be a compatibility problem with the BDP-S3200. Let’s see if there are other users with the same model that can give you some advice.
This is an issue with a lot of DLNA NAS’, such as Synology and QNAP when directly streaming to a TV/Blu-Ray Player, but it is not an issue if you stream to a Roku, Xbox 360/One and PS3/4.
Although crappy, try streaming to them as they have the hardware to support it. I understand if you put a HDD into the TV it will RR/FF, trust me, I know.
Im not too sure why to be honest.
I know there is DLNA and Twonky, try streaming via both and see if its a problem on both.