You might have to bridge the ethernet adapter on the mangoES with the usb WiFi adapter into br0 then give br0 the ip address of the mango instance.
Then you should be able to see the machine from either interface.
The default ethernet ip on mine is set in /etc/network/interfaces.d/eth0
You would have to create a bridge interface, add the eth0 and wlan0 or whichever interface it comes up as to the bridge, then give the bridge the IP Address.
Cheers
Dan