How to configure non-dsl router for VPN ports ?

Previously we used a DSL router with NAT and Firewall to allow VPN ports (500,4500 and 1701) through to a VPN server on the LAN, which gave remote access to PCs and File Shares.

Our internet supplier has changed and we now have just an IP connection to work with. We have connected this to an IP port on the router which gives us internet access and allows us to access local resources - IE. the old DSL router is still happily delivering DCHP addresses to the LAN in the correct range although the DNS (also) does not appear to be working, I'm not to bothered about that as I think fixing the port mappings will lead to a solution to the DNS problem.

The problem is that the port forwarding seems to apply only to connections on the DSL line which clearly is no good.

There must be a router that allows port forwarding off an incoming IP address to a fixed address on the LAN. Oh and since the incoming IP address is not fixed, it may change but would still be attached to the same physical port on the router.

Any takers ?

Chris Coleman.