The general “internet recommendation” is to configure your Bell 3000 to put the Asus into its DMZ list. This may require moving the PPPoE config into the Asus. There is some risk here but its similar to putting the device into bridge mode.
The added risk is you never want anything but the Asus connected to the 3000 and that includes any wifi clients. Your Asus will then be your security / firewall.