Overlapping WAN Subnets (W0-WAN and Wired WAN)

SonicOS extends WAN Load Balancing (WLB) capabilities to support multiple wired and wireless WAN interfaces operating within the same IP subnet (overlapping WAN subnets-W0-WAN and Wired WAN).

The deployment scenarios — particularly those involving WAN redundancy with a wired WAN (X1) and a wireless WAN (W0) — require to reside in the same subnet configuration to enable seamless failover between connections sharing the same upstream DHCP network. This capability is particularly useful in environments where network segmentation cannot be controlled (for example, hospital or enterprise-managed networks).

We can achieve the overlapping of WAN interface networks by making changes across several layers of the system, such as:

• Bypass the interface overlap validation specifically for WAN zone interfaces, allowing them to share the same subnet.
• Assigns routing metrics to determine preferred WAN paths:
  • Primary WAN interface (X1): Lower metric (higher priority)
  • Secondary WAN interface (W0): Higher metric (lower priority

For the traffic that hit default route, whether to forward through wired WAN or W0 is dependent on WAN Failover & LB configuration, traffic always goes out through the primary WAN.

This enables a WAN redundancy setup where a wired WAN (X1) and wireless WAN (W0) share the same subnet, with automatic failover / failback governed by route metrics.