Not sure if related, but might be worth cheching this too: http://forum.draytek.co.uk/viewtopic.php?f=2&t=16131&p=68909&hilit=DNS#p68900

Also, could you confirm the current firmware version on the 2820 please? Thanks.

I checked out the link and found the setting they were talking about. All of the DoS Defense settings are disabled already, so we can rule that out. I changed the settings so that the timeout for the key is 24 hours (on both sides) and left the data setting on the WG to 0 which should be unlimited. Then, I changed the settings you recommended on the Vigor and everything is connected.

Ahh, and here is the data you requested:

Router Name : XXXX
Model Name : Vigor2820
Firmware Version : 3.3.5.2_232201
Build Date/Time : Apr 7 2011 18:10:43
ADSL Firmware Version : 232201_A Hardware: Annex A

I'll run some tests and report back as to the reliability of the connection soon.