Airtag not found

The signal is weak most likely because the AirTag may be at the periphery or beyond the range of the Bluetooth signal emitted by your iPhone. This is something in the order of ten metres. Have you had any success in finding it by moving about your house?

In a public place an iPhone owned by another user can be close to your lost item and this is enough for an AirTag to be able to report its location to the Find My network, but in the home - especially a large home - it is entirely possible that an AIrTag will not be near enough to any iPhone to report its location either buy distance or obstacles through which the Bluetooth signal is weakened and the range reduced.

If you find AirTag unsatisfactory there are alternatives out there for you to research and compare.

AirTags are Bluetooth devices that need to be within about 30 feet from an Apple device to be able to transmit its location. To avoid the necessity of using this short range BlueTooth network, then you should look for a GPS tracking device. Of course, you will pay more for those and they generally have shorter battery life and larger footprint, but you can find many to choose from..