Scientists in Germany have demonstrated a startling new form of surveillance: identifying people using nothing more than ordinary WiFi signals. By analyzing how radio waves bounce around a room, researchers can effectively “see” and recognize individuals — even if they are not carrying a device and even if their phone is turned off.
FWIW I was able to use my own router when I set up with Xfinity recently
This was fiber, if that makes a difference. I asked the install guy, he called his boss, because no one had asked him that before. He told me “no, it’s not allowed”. Also, I tried plugging the patch cable directly into my own wifi router and nothing.