You can add a secondary IP address on any interface (e.g.) without using VLAN tagging. This is useful if you have more than one subnet on your LAN, have no VLANs but want both subnets to be routable, without using an additional physical interface.

1. Create a static ARP entry for the gateway address of the additional subnet on the interface. Select the interface on which the subnet will be on. Enable Publish ARP. This will also automatically fill in the MAC address of the selected interface.
2. Create an address object for the additional subnet.
3. Add a static route for the additional subnet:
   • Source: ANY
   • Destination: the address object you created in the previous step.
   • Service: ANY
   • Gateway: 0.0.0.0
   • Interface: the interface the subnet is on
   • Metric: 20
4. You may have to adjust firewall rules if they are very strict (by default, this is not the case).

This enables basic communication between the two subnets and the Sonicwall will forward and NAT traffic to the internet, but for a more granular control, you will probably want to adjust the firewall rules.