The title says it all, really.
The wikibooks page Tomato_Firmware/Menu_Reference#Advanced says that PPPoE must be used with gateway mode, not router mode. And indeed, when the option is set to router mode, nothing appears to work (if additional configuration is required, which seems likely, I don't know what that configuration should be or where it should go).
I would like to use a routed /29 over a PPPoE (dynamic) link. Any pointers?