On mine I could see in the notification bar that WiFi File Explorer had started, as long as I didn't let the screen go off - it puts a little WiFi symbol up in the left-hand corner (I've not touched the app's settings, because you wouldn't be able to). Can you see the notification bar through your lockscreen? I've never used Sense 4 except playing in a shop, so don't know stuff like that. The address looks correct (at least that's what works for me, sticking 8000 on the end). So could avast interfere with starting one of the apps up? Guess I'll install avast, uninstall the others, then try to repeat the process and see what happens.