When choosing an IP address for the Samb4 AD container, make sure the IP address is not part of the DHCP scope.
If your DHCP scope is the whole green subnet, change the scope to something smaller so you have some IP addresses available outside the DHCP scope for static IP assignement.
example:
You use subnet 192.168.1.x with a subnetmask of 225.225.225.0
You have your NethServer at IP 192.168.1.1 and you have DHCP giving out addresses rranging from 192.168.1.2 - 192.168.1.254
In this case all IP addresses in the subnet are within the DHCP scope.
change the DHCP scope to for example 192.168.1.50 - 192.168.1.254
This way you have all IP addresses from 192.168.1.1 - 192.168.1.49 available for static assignment. So you avoid DHCP giving out addresses that are in use by a device with a static IP address.