Novell Doc: Novell BorderManager 3.9 Virtual Private Network Deployment Frequently Asked Questions - Should I keep NAT and VPN on the same machine or on different machines?

2.2 Should I keep NAT and VPN on the same machine or on different machines?

You should always keep the NAT and VPN on separate machines.

Deployment

Before configuring the VPN services on the Novell BorderManager 3.8 machine, ensure that Static NAT is working.
Configure the VPN services on the Novell BorderManager 3.8 machine with the public IP address on which the VPN service is to run.

Testing your Configuration:

After configuring the Static NAT, ensure the traffic from the NAT to the VPN server is flowing properly.