How to Configure PPPoE on the WAN Interface of Zyxel USG FLEX H Series

This article explains how to configure a PPPoE (Point-to-Point Protocol over Ethernet) connection on the WAN interface of a Zyxel USG FLEX H firewall. PPPoE is commonly used by Internet Service Providers (ISPs) to authenticate customers using a username and password.

Before you start, make sure that:

• You have administrator access to the Zyxel USG FLEX H Web GUI

• The WAN cable is connected correctly

• Your ISP has provided PPPoE username, password, and authentication type

Local Web GUI

Go to Network > Interface > Interface 

• Edit the current profile or add to create a new PPPoE profile.

• Select the required Authentication Type (for example, PAP or CHAP).

• Enter the Username and Password provided by your ISP.

• Click Apply to save the settings.

After the configuration is complete, you can verify the connection:

• Check the Dashboard or Status page to confirm that the PPPoE interface has an IP address

• Use Maintenance > Diagnostics > Network Tool to send a ping to an external IP address (for example, 8.8.8.8)

Optional: Configure PPPoE with VLAN on USG FLEX H Series (If Required by ISP)

Step 1: Open Interface Configuration

1. Go to Network > Interface > Interface

2. In the External section, click Add

Make sure Enable Interface is turned on

Step 2: Configure Interface Properties (VLAN)

Set the following parameters:

• Role: external

• Interface Type: VLAN

• Name: Enter a descriptive name (for example: pppoe_VLAN7)

• Member:

  • Select Port

  • Choose the physical WAN port (for example: p1)

• Zone: WAN

• MAC Address: Use Default MAC Address

• VLAN ID: Enter the VLAN ID provided by your ISP

Notes and Best Practices

• If your ISP requires VLAN tagging, create a VLAN interface first and then use it for PPPoE

• Make sure the physical WAN interface does not have a static IP address when PPPoE is used

• Check ISP requirements for MTU size and authentication method

Common Issues

• Authentication failed: Check the PPPoE username and password

• No IP address: Verify VLAN settings and physical WAN connection

• Connection unstable: Confirm MTU and ISP parameters