Dear,
Thank you all your feedbacks, our engineers are doing the WiFi test with different encryption, we will find the solution ASAP, we will try our best to solve it in the next FOTA update.
Same here - with WPA/WPA2. Not too bad though. Seems to depend on field strenght. However in same location where UMI Touch conks out, my much older LG Optimus will continue. Must be the WLAN module of the phone.