> Or you could add an LTE connector and measure any signals you may receive that you shouldn't from inside a server room. Incoming Bluetooth Low Energy announc

> Or you could add an LTE connector and measure any signals you may receive that you shouldn't from inside a server room. Incoming Bluetooth Low Energy announcements should have a receive power level associated with them. Stick a beacon (like say a standard ble temperature/humidity sensor) somewhere, and you should be able to tell if the distance to it changes.