Hello,
Yes, I ask this how to configure the NIC? 
But not by the WEBGUI... by the CLI way.
I have a strange behavior, not sure NS is the cause, perhaps a Virtual Box issue:
I've got a NethServer instance in a VM on my Mac.
For one reason too long to explain here, I had to change the subnet of my home Network.
It was the 192.168.2.0/24, and now it is 192.168.20.0/24.
The Mac is on the correct network, take is IP by DHCP ( the MicroServer), but when I start the NetServer VM, it still in the old network, nothing abnormal because it's a fix IP address 
I reconfigure the nic with the CLI, via the Cent OS way...
By editing the /etc/sysconfig/netwok-scripts/ifcfg-eth0
The Nethserver on the actual network ping successfully 8.8.8.8, my gateway... But I still unreachable from the Mac !!!!!
When I restart the VM... It return to the the old network.
When I change the nic configuration... Is there the database to fix?
How to?