The Balance 20 has an extra WAN port that can be activated through a license key.
When we look at the WAN connection in the web admin interface we see 2 WAN connections and a mobile Internet connection by default.
You need to order a feature license to activate the third WAN connection.
You will need to give the serial number of your Balance 20 when you order this feature key.
Once you have received the feature key from your favourite Peplink reseller / distributor log back into the Web interface of your router and go to System > Feature Add-ons
Paste the activation key in the Feature Activation field and click “Activate”