Immediate things to try,
It looks like the latest firmware brought in full support for PPPoE.
1. Enable PPPoE on the router setup page and re-enter your user name and password.
2. Disable/remove any PPPoE client software you might have been using instead on your PC (WinPOET, Enternet, Access Manager etc).
3. Enable PPTP and IPSec pass-through on the filters admin page.