ordered a 2820, will let you know how I get on....

Can we not ask Draytek for the official stance on this?

They must be able to advise on the settings to make it work?

I now have a 2820VN and I still can't get it working despite following this post from the Vodafone site http://forum.vodafone.co.uk/topic/65939-draytek-vigor-2820n-working-config/page__gopid__430029&#entry430029

so it would appear not all Drayteks are compatible?

Hate to say it but it looks like I'll need a new router and not a Draytek

I put a call into Draytek support. They have started out helpful (we haven't fixed it yet!) - and they did remote into my router etc. to confirm what is happening. This is what they suggested at first
Note - I am on a 2910 Dual WAN, but I think much the attached applies to 2820 as well.

- Under System Management and Management, untick "Disable PING from
the Internet". Save the settings and on next page click on OK to
restart the router.

- Under VPN - Remote Access Control > untick "Enable IPSec VPN
Service". Save the settings and it will ask you to restart again.

- Under Firewall - General Setup, enable "Accept large or fragmented UDP
or ICMP packets" .

- Under NAT - DMZ host setup page, set "Private IP" option for WAN1
(assuming its WAN1 connected on your Vigor2910) interface and select the
IP address of Vodafone device.

- Telnet to the router and run a command as follows:
> srv nat ipsecpass on

After making these changes, restart the vodafone device and see if
connects OK.

I'm reluctant to change the router to another manufacturer because you can't be sure another router will do all you want, and there aren't so many Dual WAN routers out there. But I sympathise - I have spent days trying to sort this issue (and despite that the VSS does work with other routers, I have a suspicion that there is something about it that makes the whole thing flakey). Try the above, and raise a ticket with Draytek if it does not work.

Thanks I'll give it a try, I did do all those things earlier without any luck.

Whats the best way to get in touch with them?

Also no idea what this telnet thing is and how to action it?