I noticed this just yesterday. When my phone screen locks, the WiFi will disconnect and 4G will turn on. When I unlock, it takes a second to connect to the WiFi again, but the mobile data stays on. My device was manufactured without a stock mobile data toggle, so I've tried Data ON-OFF by Antonio La Rocca, Juice Defender, and a few other mobile data toggle widgets but to no avail. When I lock and then unlock the screen again, the 4G will just come back on.
I have the Connections Optimizer unchecked, WiFi is set to never sleep, WiFi power save mode is off via the dialer code but NOTHING WORKS. It seems like a very recent problem, I'm not sure if it has to do with updating the Connections Optimizer (which I removed all updates for) but I would like to fix it. I just don't want to have 4G turning on all the time when I don't need it to.
Also, I don't want to just switch to Airplane Mode because I still need to text and make calls, just don't want 4G at work when I can use their WiFi.
My version is 4.4.2. Yes I have, and it doesn't show. I even went into the settings for the notification panel and there isn't an option to add a mobile data toggle. I unchecked mobile data in the network settings, but it just turns itself back on once I lock/unlock the screen.