I have a 2910 and 2820 with IPSec VPN established between the two routers and all works fine for local users on each subnet. If I VPN in as a Dial-in user on the 2820, I can see the local network but not the other end (2910) of the VPN tunnel.
It sounds like a routing issue but not sure. Any thoughts?

Thanks.

With the VPN client you're using, does it have the facility to add more subnets that will be usable through the VPN connection? The Draytek SmartVPN client has a "More" button that would let you do that.

Not as far as I can see. I'm using Windows XP built-in client to dial in to the 2820, the 2820 has subnet 192.168.1.0. the 2910 has 192.168.2.0.
The XP dial-in can happily see the 192.168.1.0 subnet but nothing on the 192.168.2.0. subnet on the remote VPN on the 2910.
I can't see how to add another subnet to the remote dial-in user properties on the 2820 or to Windows XP VPN client.

You could try checking out the route command in Windoze to force to route stuff for 192.168.2.x via 192.168.1.x.

As an alternative, you could set up another VPN tunnel on the Windoze box directly to the 2910.

Lastly, if you have teleworkers, I suggest you get the 2820 off the 192.168.1.x subnet. Too many domestic routers use this as a default and it will mess up your VPN connection.

@themonk: can you tell the secret how you managed to use the built in ipsec connection of windows xp?

I am trying over here to make it work. And for some reason the smart vpn client does the trick. But the connection made by smartvpn (named to vigor) won't connect.
What do i overlook? Connection from an iPhone works out of the box, so it seemes to be a microsoft issue.

( wished setup default windows client at l2tp ipsec witb pre shared key )