This tutorial will show you how to configure WAN failover on Zyxel USG Series using "Spillover" on the 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
6. Set your main WAN Connection as "Active" and the Backup as "Passive"
7. Change the Spillover value on your main connection to a value higher than the default so it can change the WAN connection when he 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