This is a really old thread and I can't remember the full ins and outs of the set up.
If I recall correctly the simple answer is: there is no solution. The Vigor routers seem to make their own mind up about network hierarchy and that's just how it is - tough.
Low powered, cheap computers, even running on ARM architecture, have become available since these posts were made so many years ago. Running a Linux/BSD server on such a device will make VPNs much easier than trying to use Draytek's ridiculous implementation. No point in even trying to make these routers work without it.
Maybe the newer devices are a bit more sensible, but I doubt it.
Vigor 2800G : Firmware 2.8.1
Extremely useful: Draytek Syslog from
Router Tools
and
Wireshark
(previously Ethereal).
