Further more, if I try to play that MKV file again and it asks me to 'Resume playing at last point' I MUST pick NO if I want to watch the file. Pressing the arrow keys usually causes a complete jump to the next movie. With Linux and ZFS, QuTS hero supports advanced data reduction technologies for further driving down costs and increasing reliablility of SSD (all-flash) storage. Playing an MKV file, I can ONLY FFWD and REW. QuTS hero is the operating system for high-end and enterprise QNAP NAS models. WIth Linux and ext4, QTS enables reliable storage for everyone with versatile value-added features and apps, such as snapshots, Plex media servers, and easy access of your personal cloud. so you should get a player that supports mkv, the new NMP-1000 by qnap maybe. Mezzmo is the ultimate media server for streaming movies, music and photos to your UPnP and DLNA devices and web browsers. QTS is the operating system for entry- and mid-level QNAP NAS. it always depends on your player (client) what it can handle, the NAS/DLNA server is just there to serve it (no matter which product you choose) and of course the TS/twonky support mkv too.