How to Continue Connecting Remotely?

[kiroboy69]

I have an XP computer with a static IP address and a Sonicwall router that is configured to allow this computer to be connected to remotely.

I want to replace this computer with a new one.

When I take the old computer off the network (disconnecting ethernet cable from back of pc) and bring up the new one in its place (same static IP address as old pc), I try to connect to it from outside the network (public iport) and I am unsuccessful.

What could be preventing me from connecting to this new computer remotely even though it has been given the same IP address as the old computer?

Remote Desktop is enabled in system properties and windows firewall...

 

[Tmagic650]

"I want to replace this computer with a new one"...
Is this "new' computer also running XP?

 

[kiroboy69]

Yes, the new computer is running XP SP3, and I am able to connect to it from within the network using remote desktop and its local static IP address.

Does it matter if the new one is not joined to the domain as the old one was? Do you think it has to be a part of the domain with the same computer name as the old one?