I have tried it with a QNAP TS-453D (with QTS 5.0.1) but was unsuccessful, not even after lengthy research and numerous trials. I firmly believe the K4 ISIO has software / firmware problems for using it with with NAS devices. Even though I have no Synology SAN to try, I strongly suspect that would not work either.

I'm using the device with an USB SSD device without problems though. Transferring anything I'd like to preserve to that QNAP device is no problem though, just a bit of work (as usual :-). (I use WinX HD Video Converter.)

Good luck.