WD TV and Plex DLNA issue

When I connect direct to a .mkv 1080p file on my server it plays no problem. But if I connect through the Plex Media Server using DLNA the same .mkv files will stutter and keep rebuffering rendering it unwatchable. Any ideas? Thanks!

I haven’t use that DLNA server check the link below to see if that can help

http://community.wdc.com/t5/WD-TV-Live-Streaming-Discussions/Help-w-Plex-Media-Server/m-p/428776#M9987