This may be a problem with the bandwidth of the wireless network when streaming to the Roku or it is a problem with transcoding speed of the Mezzmo server. You can try pre-transcoding an ISO file in Mezzmo then stream it to the Roku and if it plays without issue then the problem is the transcoding speed, if it still has a problem then it is bandwidth and you may need to run a wired cable to the Roku to stream the content or change the Performance settings in Device Settings to lower the bitrate or resolution when transcoding.