So with my nexus 5 im easily able to do something like this to connect adb over wifi:
adb tcpip 5555
adb connect 192.xxx.x.xx
and then disconnect the usb cable. I have another device im trying to connect (Dell venue 8 tablet) but it seems to disconnect from the adb wifi connection a split second after the usb is pulled.
I use the same commands:
adb tcpip 5555 (<- without another device connected)
adb connect 192.xxx.x.xx (tablet ip here)
Executing adb devices after this shows both the wifi adb connection as well as the usb connection, but with the tablet, as soon as I kill the usb connection, the wifi adb connection also terminates.
Does anyone have any thoughts on why this may be happening?