I have a dedicated PMS and a dedicated Home Theater server. All of my media is in MP4 format I have all the options, Direct Play, Direct Stream, Allow Direct Play of AC3 Audio, & Prefer AAC Audio checked/enabled. If I play the movies through my PS3 DLNA (not using Plex) there is no problem with playback. However, anything I play through Plex the video is choppy multiple times per second. The problem does not seem to be network-related. I'm running the latest server version 1.3.3.3148. My dedicated server stats are below:
Home Theater
Win 10
Intel Core 2 Duo 2.33 GHz
4 GB RAM
PMS
Win 7
Intel Pentium 4 2.4 GHz
2.5 GB RAM