I had the same issue with my device (Note 3). T-Mobile doesn't seem to have 

a "Connection Optimizer" feature in its line of phones. In T-mo's 

case the feature that needs to be disabled is the "Wi-Fi Manager". 

To disable this feature you need to do the following: 



Access your T-Mobile account (for me I just press on the "T-Mobile 

My Account" App). 



Press the menu button on your device, then select "Options". 



Under "Notifications" uncheck the box marked "Display Wi-Fi 

Manager notifications". 



Under "Connection Assistant" select "Open Wi-Fi manager". 



Uncheck the box for "Manage Wi-Fi Connections". 



That's it... 



I talked to T-mobile tech support about an unrelated issue and 

offhandedly mentioned this problem. The rep informed me that this 

was a known issue and stated that this issue was being addressed. 

In the mean time disabling the "Wi-Fi Manager" is a temporary fix 

to address this problem. Here is the shorthand way to disable the 

Wi-Fi manager:



T-Mobile My Account -> Menu -> Options -> "Display Wi-Fi Manager 

Notifications" (Uncheck) -> "Open Wi-Fi Manager" (under 

"Connection Assistant") -> (Uncheck) "Manage Wi-Fi Connections".