One of the features that make Peplink routers stand out from the competition is the way they deal with firmware upgrades.
Michael Horrowitz has written an article on this feature on his website.

The Ninja’s View
The dual boot feature of Peplink routers is another built-in feature of Peplink routers that makes it so much easier to test beta firmware versions and upgrade the firmware on your router with an easy option to roll back to the previous firmware.
That, and the ability to update the firmware using InControl makes firmware management a breeze.