ADB over wifi goes away after unplugging usb
I am not sure it may be this the case, or it may be helpful, but I got the same message, and it worked if I enable adb via WiFi with the command 'adb tcpip 5555' (from the PC) when the PC is connected to the phone hotspot but the phone is NOT connected to the internet (i.e., 3G is deactivated). 
In short, I did the following:


Plug the device via USB
Restart the phone
Disable phone data
Enable phone hotspot
(adb usb)
adb tcpip 5555
Unplug the device
adb connect 192.168.43.1:5555


After that, I reactivated 3G on the phone, and I had both the internet hotspot and the adb connection, at the same time.