by Howard Miller.
Ken- I think you are probably wasting your time. The OP now sees his rather weird set up as somehow 'normal' and is determined that Moodle is the barrier. I don't wish to sound so combative, but that is the case.
Moodle works by constantly rewriting destination URLs and needs to understand the base web root. This is sensible and provides a degree of security (it's very hard to hack a fixed web root).
In a production environment, you shouldn't really be using IP addresses for your destinations anyway. There's not much anybody can say to convince me that this is anything other than a DNS/Routing issue. I appreciate it's a tricky one, but please don't blame Moodle because your configuration is overly complex