To configure IPv6 on an Asus RT-N66U router, log in and enter the IPv6 setup page by selecting ‘Advanced Settings’ > ‘IPv6’.
Configure the settings on this page per the the following:
Connection type: Native Interface: PPP DHCP-PD: Enable Accept Default Route: Enable Auto Configuration Setting: Stateless Connect to DNS Server Automatically: Enable Enable Router Advertisement: Enable
Thanks to Josh. H for testing and supplying us with this information!