I've had my G4 about a month, and I've noticed that my wi-fi will disconnect, I'll get a message saying "disconnected from (router name)," and then after several minutes of connecting to mobile data, it reconnects on its own to the wi-fi. I have this occurring on both my home network, and my work-provided network, so I don't think it's specifically a problem with my home network. I'm also not having any trouble keeping other devices connected at home. Is this a known bug with this phone, and will there be a software update soon to correct this?
There is another setting you can toggle off. If you go to Settings, Networks and just touch the blue WiFi button, you will see a list of your current WiFi networks.
In the upper right hand corner are three dots behind the word Search.
Press only the three dots and and select Advanced WiFi from the drop down.
-Switch to Mobile Data when Internet is unavailable via WiFi.
-Disconnect WiFi automatically when signal is weak.
The Connection Optimizer and these setting try to keep you always connected to the best network.Unfortunately, the slightest loss of internet connectivity cause your phone to jump off the WiFi. Some ISP's have more connection blips than others.You don't notice it when you are reading a Web Page or streaming because your content has already been downloaded, however the phones tend to pick these Internet drops and blips and kick you off Wi-Fi and back on the Mobile internet.