1. AirTies 4920 & 4921: To expand your Wi-Fi coverage and still take full advantage of our Wi-Fi gateway mesh network, you have to use an AT&T AirTies 4920 or 4921. Non-AT&T AirTies won’t be able to take full advantage of all the features of the AT&T Smart Home Network and the Smart Home Manager app. AT&T-branded AirTies 4920 or 4921 won’t work with non-AT&T branded Wi-Fi gateways or third-party internet services.