Please, someone,
Explain me how can be possible a Windows 8 computer with IP 10.2.10.10/255.255.0.0 talk to a 10.0.0.1/8 RouterBOARD
That is:
10.2.10.10/16 ( 255.255.0.0 = /16 right? )
10.0.0.1/8
They can talk each other, even in different subnets!
Tested this with a PC-to-PC (same address, just replaced the RouterBOARD with another laptop) and does not have worked as in RouterBOARD.
Thank you.
This is probably not the answer you are hoping for but I don’t know how to explain this.
I’m guessing it’s the same as when you are trying to access www.google.com from your computer. The google server also has an IP address not in your local subnet but you can still access that 
I believe the subnet is only used to ‘identify’ a local network so your computer “knows” where to look for a certain IP address, it doesn’t mean you cannot access that particular IP.
There are not in different subnets… 10.0.0.0/8 includes 10.2.0.0/16
And for a direct connection this is not relevant, as long as there is no firewall to prevent that and ARP requests are properly served.
Pinging from 10.0.0.1 will send an ARP request on the interface (since 10.2.10.10 is in 10.0.0.0/8).
The windows machine will respond since ARP is classless.
And from that point on communication is possible.
The reverse way is also possible because 10.0.0.1 is the default gateway.
What makes me wonder is why windows accepts a gateway outside its ip/mask range…
Could you check using ipconfig what the actual mask is on your windows interface. I suspect it is /8.