Comcast is activating Wi-Fi motion sensing on millions of compatible Xfinity gateways, allowing the routers to detect movement by measuring disruptions in signals between the gateway and connected devices. The free feature, part of Xfinity Shield, can send activity alerts through the Xfinity app and offers Home, Away, and nighttime monitoring modes without requiring separate motion sensors. The Verge reports: Wi-Fi motion sensing is a technology that has been around for a while, but it's only recently that it's become accurate and reliable enough to catch on. Linksys launched a similar service in 2021, but discontinued it a few years later. Lighting company Wiz launched a line of Wi-Fi-sensi...