@Boken-Lin Better not, the risks are too high that I destroy it. Better stay with the Plug n' Play option of having a ethernet expansion. Could you send me one?

@Boken-Lin Nope! Do I need one?

@Boken-Lin This is what I got:
athr_gmac_ring_alloc Allocated 640 at 0x838cb800
athr_gmac_ring_alloc Allocated 4032 at 0x838a9000
Setting Drop CRC Errors, Pause Frames and Length Error frames
Setting PHY...
athr_gmac_ring_alloc Allocated 640 at 0x838cb400
athr_gmac_ring_alloc Allocated 1536 at 0x83965000
ATHRS26: resetting s26
ATHRS26: s26 reset done
Setting Drop CRC Errors, Pause Frames and Length Error frames
Setting PHY...
device eth0 entered promiscuous mode
device eth1 entered promiscuous mode
ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
Port Status 1c000004
ar7240-ehci ar7240-ehci.0: ATH EHCI
ar7240-ehci ar7240-ehci.0: new USB bus registered, assigned bus number 1
ehci_reset Intialize USB CONTROLLER in host mode: 3
ehci_reset Port Status 1c000000
ar7240-ehci ar7240-ehci.0: irq 3, io mem 0x1b000000
ehci_reset Intialize USB CONTROLLER in host mode: 3
ehci_reset Port Status 1c000000
ar7240-ehci ar7240-ehci.0: USB 2.0 started, EHCI 1.00
usb usb1: New USB device found, idVendor=1d6b, idProduct=0002
usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
usb usb1: Product: ATH EHCI
usb usb1: Manufacturer: Linux 2.6.31--LSDK-9.2.0_U11.14 ehci_hcd
usb usb1: SerialNumber: platform
usb usb1: configuration #1 chosen from 1 choice
hub 1-0:1.0: USB hub found
hub 1-0:1.0: 1 port detected
Initializing USB Mass Storage driver...
usbcore: registered new interface driver usb-storage
USB Mass Storage support registered.
**** drop_caches_sysctl_handler: all done timer added ...****
Starting pid 218, console /dev/t
(none) mips #6 Fri Aug 28 16:51:14 CST 2015 (none)
(none) login:

@Boken-Lin On both boards: The amber led does not blink during startup and I cannot set it up via wifi. What is the solution for that? If I read this thread, there are several solutions, some works some not according to the people. What is the official statement and solution?

Same here... Two unities bought. Took long to arrive. After arriving, both are not working. I'm not an expert in such environment and there are several directions on how to solve it creating some confusion. Please create a fixed topic, or a tutorial, with clear steps on how to solve this issue. Since I paid for it, I would expect a WORKING device out of the box and not something that you have to fix it by yourself. At the moment, the level of frustration is so high that I gave up of any trial.