How can I debug an Android device without cable(Not even without the initial connection)

Question

Typical way is

1. Connect PC to the device with USB Cable.
2. adb tcpip 5555
3. adb connect 192.168.xxx.xxx:5555

However, what if the device manufacturer doesn't recommend this way. But connect them directly wirelessly?

What they say is

1. PC and Device must use the same Wifi
2. Check IP address of the device.
3. adb connect 192.168.xxx.xxx:5555

And I found this blog that says I don't need to connect USB to the real device. But run anything adb to detect any one device.

1. Run an emulator.
2. adb tcpip 5555
3. adb connect 192.168.xxx.xxx:5555

However, I get Connection refused error with the second and third method. What should I do? How can I debug this device?

*The port 5555 is not being used.