TP-Link TL-WA901ND manual  Used as WPS button

TL-WA901ND

300Mbps Wireless N Access Point User Guide

Used as WPS button:

If you have client devices, such as wireless adapters, that support Wi-Fi Protected Setup, then you can press this button to quickly establish a connection between the Access Point and client devices and automatically configure wireless security for your wireless network.

Wireless antenna: The external antenna is used to transmit and receive wireless data.

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