VPN configuration without 2 network interfaces

Hi I hope someone can help here, I want to create a VPN connection for multiple computers, to use the same ip address or one I allocate.

It appears I can only do this if I have two network cards, is there a work around or do I need to have a server with two NIC?s?

As when I try to configure the VPN I get this message
network interface custom configuration path

If it is impossible can anyone recommend a uk dedicated server with more than one network interface

Thanks in advance
Stephen