Due to the complicated nature of the Dual-WAN setup, port forwarding is not supported by the regular port forwarding utility. To forward a port, follow these steps.
Make a backup
On the bottom of the screen, click System
Scroll down to Configuration Management & Device Maintenance
Click “Download” under “Back Up Config”
Navigate to Firewall/NAT > WAN_IN > Actions > Edit Ruleset
If the destination device is already listed, click Actions > Destination and append the port to the “Port” field
Skip to step 10
If the destination device is not listed, click “Add New Rule”
In the Add New Rule popup box, enter a brief description (no spaces allowed)
Action: Accept
Protocol: [choose]
Under the “Destination” tab, enter the IP address and ports (comma separated or hyphenated, no spaces)
Click “Save”
Move the rule (click & drag) above the “Drop invalid state” rule
Click “Save Rule Order”
Navigate to Firewall/NAT > NAT and click “Add Destination NAT Rule”
Enter a short description (no spaces), followed by “_eth0”
Select eth0 from the “Inbound Interfaces” menu
Enter the device IP address and port in the “Translations” area
Enter the public port in the “Dest Port” port field (required!)
Enter the private port in the “Translations” field (required!)
Click Save
In the list of Destination NAT Rules, find the newly created rule and click Actions > Copy
On the duplicate rule, click Actions > Config
Change the “_eth0” to “_eth1” in the description
Change the “Inbound Interface” to eth1
Verify that the port properly forwarded (test the application)