Ok, I don’t understand too much italian but if you’re talking about a problem with a intel atom based board wich have a Realtek 8x series that support 1000/T and when you verify the connection is at 1000/T but you realize that it only support 100/T because it connect to a 100/T device, this is a known bug for the zeroshell centos kernel and it is solved in newer versions. You can do the following:
1. Unplug the ethernet cable.
2. Turn on the zeroshell
3. After it finished booting, plug again the ethernet cable
Now it should work, seems to be that the bug appears when you turn on the computer and the cable is plugged.