How is presence detected to start with? based on network activity? DHCP ?
I noticed that my Android phone tends to be detected when is at home (or away) more reliable but not always.
My wife's iphone6 is a total hit or miss. When it's detected to be away, it may be declared so about 10min later. Some times its presence is not
detected at all when its back.
I experimented a bit with the inactivity grace period but from what I read this is only intended to assist with the case where
some devices may cut off wifi when it's used for phone calls (

).
Any comments or suggestions?