Device and development computers must be in the same network.
So you need to check if your emulator has a correct connection.
10.0.2.2 is a special alias to your host loopback interface (i.e., 127.0.0.1 on your development machine)
- Communication with the emulated device may be blocked by a firewall program running on your machine. 
- Communication with the emulated device may be blocked by another
(physical) firewall/router to which your machine is connected.
Check your devices with
- tns deviceand- adb devicesthen ping to their IP or- telnet localhost 5554
 
Your host computers local IP address can be different but just use 10.0.2.2
Vue.use(VueDevtools, { host: '10.0.2.2' })