There are many reasons why your airtag not reachable. Check if there is a battery problem, or if it does not reach your specific range. Airtags can reach no more than 30 to 35 feet. If you go this particular distance, you will lose your AirTag connection. Also, some of the technical difficulties are there to connect with your Apple Airtag devices. The user must know the cause of why is the Airtag device not connected to the iPhone device.