Air tag
I bought the 4 pk for my cats while I’m away. It keeps saying I need to move closer, can’t detect
Question marked as
Your iPhone needs to be within Bluetooth range (~30-40') of the AirTag in order to "see" its location on the Find My app on your phone.
The Apple AIrTags rely on Bluetooth and the Apple Find My Network. That network is either your iPhone or any other iPhones within Bluetooth range of the tag to relay both the tag's ID & the phone's GPS location over the Internet to the Apple servers. This is where you would see updated location information with the Find My app.
FWIW, these tags are primarily designed to help you locate a misplaced item. They are NOT designed for tracking. Whether that is for people or pets. If your goal is to keep track of where your cats are, you should consider getting dedicated tracking devices that rely on GPS, not Bluetooth.