WDTV Live/Synology NAS Maximum Bitrate?

I’m trying to stream mkv movies from a Synology DiskStation 713+ to a WDTV Live with the latest firmware. I’m using a  gigabit Ethernet connection. The WDTV Live is doing all the transcoding and the DiskStation is doing nothing more than serving the files via HFS. All of the Blu-ray movies that have bit rates of less than 20Mbs seem to stream fine, but anything above that tends to stutter, regardless of the overall file size.

Does the WDTV Live have a bit rate limit or is there something else I need to do to make these two devices play well together?

The Synology may be 10/100/1000 but the WD is only 10/100