Hmm, it's not working: it got through the indexing, then it created a whack of folders in the ix4's BTSync folder, it transfered about 24MB of files, then it stopped. Could it be because I don't have a port open for the ix4 on my router? I'm only syncing folders on the LAN for now (I've unchecked Use Relay Server and Use Tracker Server). I'll have to investigate and report back. I can report something odd: if I log onto BTSync on the ix4 (via my-ip:8888/gui/en/index.html), then click on Folder Preferences, the tabs are reversed (see below): the General tab shows 'Advanced' settings and the General tab shows the 'Secret' fields. The reverse of how it behaves/appears on the PC. BTSync on the ix4 is version 1.1.70. Edited to add: I'm giving up on the ix4-300d - it's a very disappointing NAS. I've ordered a Thecus N5550 - the company is a lot more hacker-friendly, and per their forum, BTSync works on it - see their third Party Modules discussion topic. Once I can confirm it works, I'll report back. (It works! See my post later on.)