We just created a VPN on w2k server with sp4. When we do the test, we receive different errors depending on the OS or some thing else that we don’t know. For instance, some of XP clients may receive error 800 - Unable to establish the VPN connection while some w2k get error 678 - There was not answer. Most clients receive error 721 - Remote PPP peer or computer is not responding. It is very frustrated. How do we troubleshoot these errors?