An ISP might not know that you are using an AirPort Base Station with AirPort 1.3. Because of this, they may try to have you enter a private IP 192.x.x.x address into the AirPort Admin Utility. However, AirPort 1.3 does not allow you to manually assign an IP address.
Follow these steps to set up an AirPort Base Station with AirPort 1.3 software and PPPoE for a connection to the Internet:
2. Click Configure and enter your password.
3. Click the Internet tab.
4. Choose PPP over Ethernet (PPPoE) from the Connect using pop-up menu.
5. If required by your ISP, enter your user name, password and service name in the appropriate fields.
6. Click Update.
7. After the base station restarts itself, quit the AirPort Admin Utility.
Note that you can also configure the AirPort Base Station to connect automatically. In that case, simply open your Web browser (or other Internet-based application) to connect to your ISP.