Hi Ian,
best place for the answers will be the Synology forum. Obviously not as good as HH though

I was googling for IP Cams the other day to run with my 411j.
This was a useful page Synology release a wide selection of NAS systems and it can be difficult to keep track. What is the difference between the DS211 and the DS211+ and DS211J ? Many people seem to be confused with the Synology naming conventions, but it is surprisingly easy to break down.
�+� series = performance range.
standard series (no digit) = mixture of performance and storage.
�j� series = entry level consumer, concerned about capacity but not performance.
DS = Diskstation
First Digit = number of bays
Second numbers = year for the release