title: adb wifi often go offline, how to keep adb online?
body: <p>I'm using Android tablet communicating with a USB device through USB port, the tablet only has one usb port, so I use adb wifi as my debug tool. However, when I connect adb through WIFI, the connection won't keep long(only a few minutes us usually), how to keep the adb wifi connection online all the time? 
  Another question, is it possible to use USB HUB to connect the tablet with both USB flash-drive and my computer, and keep adb running?
  Many thanks!!!</p>