LAN Additional Subnet
Use this screen to configure IP alias and public static IP.
IP alias allows you to partition a physical network into different logical networks over the same Ethernet interface. The Zyxel Device supports multiple logical LAN interfaces through its physical Ethernet interface with the Zyxel Device itself as the gateway for the LAN network. When you use IP alias, you can also configure firewall rules to control access to the LAN's logical network (subnet).
If your ISP provides the Public LAN service, the Zyxel Device may use a LAN IP address that can be accessed from the WAN.
Click Network Setting > Home Networking > Additional Subnet to display the screen shown next.
Network Setting > Home Networking > Additional Subnet
The following table describes the labels in this screen.
Network Setting > Home Networking > Additional Subnet 
IP Alias Setup
Group Name
Select the interface group name for which you want to configure the IP alias settings.
Click this switch to enable a logical LAN for the Zyxel Device. When this is enabled, the following fields will be configurable.
IPv4 Address
Enter the IP address of your Zyxel Device in dotted decimal notation.
Subnet Mask
Your Zyxel Device will automatically calculate the subnet mask based on the IPv4 address that you assign. Unless you are implementing subnetting, use this value computed by the Zyxel Device.
Public LAN
Click this switch to enable or disable the Public LAN feature.
Your ISP must support Public LAN and static IP.
IPv4 Address
Enter the public IP address provided by your ISP.
Subnet Mask
Enter the public IPv4 subnet mask provided by your ISP.
Offer Public IP by DHCP
Click this switch to enable the Zyxel Device to provide public IP addresses by DHCP server. Otherwise, click to disable.
Enable ARP Proxy
Click this switch to enable the Address Resolution Protocol (ARP) proxy. Otherwise, click to disable.
Click Cancel to restore your previously saved settings.
Click Apply to save your changes.