Following up on the investigation I’ve been doing to see if I could provide a reliable Edge driver to detect cellphone presence on home LAN. Unfortunately I’ve hit dead ends. I’ve tried a couple different techniques and none are reliable for iPhones. It comes down to the way they go into a deep sleep when on battery and not used for a period of time. They disappear from network tables, and even upon returning home can continue to appear disconnected if the phone is asleep. Looks like Apple is doing everything they can to preserve battery life by keeping network connection to absolute minimum.
For those of you with Android who might want to pursue this further, I have a Python test program you’re welcome to try running for a few days to see if reliable tracking is at least feasible for Andriod phones. It can run on Linux (including Raspberry Pi) or Windows. I can post it to github and provide the link here if there is interest.