The Aprilaire Wi-Fi thermostat uses an 802.11b/g/n 2.4 GHz Wi-Fi alliance certified radio and is compatible with most residential 2.4 GHz Wi-Fi networks. 802.11ac networks are not supported unless they are dual band capable.
Dual Band Routers:
Aprilaire Wi-Fi thermostats can be used with dual band access points or routers. Dual band access points or routers broadcast two (or more) wireless networks (SSIDs); one (or more) in the 2.4GHz band and one (or more) in the 5GHz band. The Aprilaire Wi-Fi Thermostat is only able to connect to wireless networks operating in the 2.4GHz band (802.11 b/g/n radio). Please configure your dual band router to have two different SSID: one for the 2.4 GHz and one for 5GHz. Connect the thermostat to the 2.4GHz SSID.