WAN Failover via trunk of a USG

This tutorial will show you how to configure WAN failover on Zyxel USG Series using "Spillover" on the trunk.

After completing these steps, your device should be able to swap to the passive interface whenever an interruption of the connectivity is detected.


1.  Configuring the WAN trunk

2. Enable Connectivity check on the active WAN trunk


1. Configuring the WAN trunk

1. Access your device by entering its IP address in the browser address line and login by using the device’s credential

2. Make sure you have a second WAN connection available.

3. Navigate to

Configuration > Network > Interface > Trunk




4. Add a new User Configured Trunk.

5. Choose "Spillover" as Algorithm and "Outbound" as Index. Set your main WAN Connection as "Active" and the Backup as "Passive". Change the Spillover value on your main connection to a value higher than the default so it can change the WAN connection when the USG can't reach it.


8. After setting up the new Trunk, you now need to change the Default Trunk Selection to the newly created Spillover Trunk.




2. Enable Connectivity check on the active WAN trunk

1. Navigate to

Configuration > Network > Interface > Ethernet


2. Select the WAN interface that is set to be your main connection. In this example, wan1 interface is used. as the active interface. Click edit on the button to open the interface settings and scroll to Connectivity check section.


3. Configure the settings:

  • Check Period: 5 seconds (How many seconds pass between connection check attempts.)
  • Check Timeout: 1 second (How many seconds to wait for a response before the attempt is considered a failure)
  • Check Fail Tolerance:1 time (How many failures need occur before the USG stops routing through the gateway)
  • Check this address: It's recommended to use this option to check the connectivity, as this will use an IP address in the internet (such Google DNS server 



Note: If the Default gateway is used, the local connection to the ISP device might work while the issue could be located in other part of the ISP network, leaving the USG without access and not detecting this as an issue


There is also a second way to achieve a failover on your firewall by policy routes:



This should be enough to make your WAN failover work.

Articles in this section

Was this article helpful?
9 out of 12 found this helpful



Please sign in to leave a comment.

  • Is there a quick way to see which WAN is active ? or see bandwidth on both WAN together ?

  • Not clear what you mean quick way - in interfaces you see all actives WANs.

  • @... : Exact. Network->Interface->Port->Port Configuration.

    it could me more visual & clear with a green/red icon.

    The Port Statistics Graphic View can be more clear is we want to see both WAN trafic at the same time without opening 2 tabs.

  • Greetings! 

    Dear Vincent,

    Thank you for your comment, please create a request to technical support, we will do our best to solve your problem.  Contact Support | Zyxel Networks