NEED HELP FINDING LOST IPHONE please read below:

How come my sons phone that has been “lost” (or dead & FORBIDDEN to be taken outside won’t show the last lost known location of the iPhone? BTW it only worked connected to WiFi, however was almost dead and left in one of the complex’s but no way of tracing it or playing a sound to it (bc it was dead) now it’s been since the 2nd week & January, and I keep putting lost mode on but when I went to upload from a backup when connecting his Apple ID to another device it showed a backup done at the end of February? Can i track it by the IP address to get the last know location? Or the MAC address? Any knowledge on this subject would be great!!! Thanks in advance