Hello,

The Device Priority (also known as QoS or Quality of Service) feature prioritizes the network traffic for specific client devices in the mAX home network.  Gaming or video streaming devices can enjoy high performance over other client devices during high Internet usage.

Also this articule could help you check it out:

https://arris.secure.force.com/consumers/articles/General_FAQs/mAX-Routers-Device-Priority-Setup

Siuu1994