I have a little more information. Firstly, I was confused why I was getting the "Out Of Sync" message on the Andoird client. This is a "backup" or "read-only" share, so surely it should know nothing of the other clients syncing with it - how can it go "out of sync" with nothing? I then found that this message appeared if a file within the directory was deleted whiles Sync was running. If I did a full Exit of the application, and then re-started it, this error would often clear on the Android client, and syncing would then sometimes continue. So, the 'fix' here appears to be - only open Sync when you want to sync files. Leaving it running 24/7, having it auto-start at boot, etc. will probably result in folders shared read-only going "out of sync" on the Android client, and not syncing to other clients. Secondly, my hunch about the Ubuntu "receiving" clients going "out of sync" when I changed the .sync/IgnoreList files appears to be correct. Whenever I changed the .sync/IgnoreList file, the Ubuntu client would go "out of sync". The only way I've found to use the IgnoreList file would be to "disconnect" the share, completely clear out the directory, except for .sync/, edit the IgnoreList file, and then re-connect the directory with the key from the Android clients and start the entire sync again. This is obviously far from ideal, but it's the only way I've found of making changes to the IgnoreList file and then still have the sync work. Separately, I'm having lots of issues making the IgnoreList file do what I want.. if I want to ignore, say, all MP3 files in <share top-level>/Music/Albums/<several directories of different depths>/ ...I have not yet found a way of entering a line in IgnoreList that works. Entries which don't appear to work include: Music/Albums/*.mp3 Music/Albums/*/*.mp3 /Music/Albums ...etc */Music/Albums ..etc I've ended up just doing *.mp3 which ignores all mp3 files throughout the whole share, which isn't exactly what I want. Ideally, it'd be nice to be able to enter IgnoreList entries as regexps, but I can see that this might be a bit complicated to explain to the average user. This is all an aside, though - the "out of sync" issue is what's causing me the biggest headaches at the moment. Cheers --Dave