Hi, I have the same problems with my Z5 Wifi, it turns off when locking the screen and then it comes up again, after 2 seconds, when I turn it up again. But what i've noticed is that it only happens when i'm connected to a 5Ghz signal instead of 2.4Ghz. If I switch to the "normal" signal, 2.4, it keeps connected. I have the WIFI ON set in always, and i have Android 6.0, so there is no Stamina options. I've unchecked also the com.sony.wifi option to be optimized with this Doze thing. Still waiting for a fix!!
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