Zend certified PHP/Magento developer

Why doesn’t my Win10 laptop automatically connect to my iPhone hotspot?

I have a laptop running Win10 and an iPhone 6. My home internet connection is spotty and often drops. But I have my iPhone hotspot on all the time and my PC wifi is setup with the “connect automatically” box checked for the hotspot–but when my home network drops, the laptop never automatically switches to the iPhone. Why not and can I fix that?