I have friends whom i help out. They have XP pro sp3 laptops behind a netgear adslmodem/router with nat and upnp enabled.
When their RA invitation arrives it only contains the local private ip not the public ip. Even when i edit into the ticket the public of the router it still goes down the tubes ! i.e dns cannot be resolved. All the firewalls etc have exclusions so shouldn't be a problem. I can and do logon to their router so addressing shouldn't be a problem.