#isp

Your router can already tell when someone walks past it — Comcast now offers that as a feature

Xfinity WiFi Motion turns the radio link between your gateway and a smart speaker into a movement sensor, with no camera and no hardware to buy. It is opt-in and off by default, which most of the alarm about it gets wrong. The real question is what a log of when your home was occupied becomes once your ISP is holding it.