This usually means the transmit power for your WiFi access points is too strong. If you imagine drawing a map of your property, plotting the location of your wifi access points, and then drawing a virtual circle around them that represents wifi coverage, then you want as little overlap as possible between access points, and you do this by adjusting down the transmit power. Although some less expensive and less configurable access points probably don’t offer the feature, prosumer and enterprise gear does. Some signal overlap between access points is unavoidable if you want to also completely eliminate all deadspots on your property, but with minimal overlap your device should be dropping a distant access point as you move out of range and pick up the closer one with the strong signal.

Most people think more power equals more better when it comes to access point signal strength but that’s not really how it works because WiFi is 2-way communication and your mobile device is always gong to be the weak link because it has the weaker transmitter. There’s no reason to broadcast a maximum strength signal from an access point if you have more than one of them.

Much has been written/documented on this topic and you should have enough keywords in the previous two paragraphs to find all the expert instructions for doing it that you could possibly need.