Peplink regularly releases newer firmware to add new features and fix bug. Having the latest firmware on your Peplink will ensure access to the latest feature and a trouble-free deployment.
Always use the latest firmware for a new deployment.
The latest product firmware and user manual can be download at http://www.peplink.com/support/downloads/
Older product firmware can be found in the firmware archive at http://www.peplink.com/support/downloads/archive/