Modify Existing WAN Route:
The default WAN route must be modified to enable Proxy ARP. The default route for any
interface cannot be deleted or modified other than to enable the Proxy ARP feature.
From the SYSTEM > ROUTING page select WAN to edit the default route of the WAN
interface.
Enable the Proxy ARP feature by checking the checkbox.
After making configuration changes, be sure to click Apply to save those changes to
RAM.