Why does my device hold onto weak (bad) wifi signals?

[AC Question]

Here is the basic point... Let's say I leave my house to take my dog on a walk. As soon as I am out of range of my AP, my little wifi icon goes from white to a gray outline. But the device will stay like that for much too long. I will try, for example, to ask Google Now a question and it will tell me that it can't connect to Google. I am in range of LTE, but because the device is still - for some reason - connected to wifi, I get no service. What I don't understand is why the device won't immediately check LTE if the wifi signal is not reaching the internet. It has been like this on every android device I have ever had. Right now I am on a Nexus 5, fully updated.

 

[B. Diddy]

Welcome to Android Central! Go to Settings>Wi-fi, tap Menu>Advanced, and look for options like Avoid Weak Signal, or Smart Network Switch. These options aren't necessarily available on all devices.