Fauxmo can not find by Echo dot 3rd gen

[gibo77]

After flashing Fauxmo to ESP8266 ESP12, it says on the serial monitor that ESP8266 is connected. But I could not ping it. Looking at the router, the MAC address is there, but the device name and IP Address is "unknown". So Echo Dot 3rd gen could not find the device.
The heap printf in serial is constant and have lots of space, so the chip is working, except that the Wifi is not functioning.

I flashed with normal AsynchTCP simple_server program. It worked fine. I can see the device name and IP address in my router.

[gibo77]

Update: I made it work.
If you are using the External Webserver of me-no-dev AsyncTCP, change the port number of AsyncWebserver not equal to 80. Port 80 is already used by Fauxmo Alexa.
So the example in Arduino IDE, Fauxmo_External_Webserver something like that is erroneous I think. You will not get connection properly with Wifi. In my case it drops out of Wifi.
So after I change the port number, it worked.
So now you have Alexa and your phone mobile controlling your light.