Why doesn't my Note 5 automatically connect to my home WiFi when I reached home?

[AC Question]

After I am in the house for a long time, I found that my Note 5 is still not connecting with my home Wifi. I need to press the Wifi icon on the flipped down menu on the home screen, only then the phone starts to connect to the Wifi, successfully. Why is the connection not automatically initiated when the WiFi connection is available?

 

[anon(632115)]

If your wifi on your telephone is switched off it cannot tell there is a connection available.