Apples sixth-generation AirPort Extreme was released in 2013, but the AirPort Extreme it and its AirPort brethren were officially discontinued in 2018.
Should I replace AirPort Extreme?
When it no longer delivers the speed that your Internet provider is supplying to you. When there is a newer feature provided by another router system that you need that the AirPort Extreme cannot provide.
Is AirPort Extreme discontinued?
Discontinuation. In approximately 2016, Apple disbanded the wireless router team that developed the AirPort Time Capsule and AirPort Extreme router. In 2018, Apple formally discontinued both products, exiting the router market.