I am not a techie but some people ask me to do things anyway, so please bear with me.
As an example let's say that the main part of a website resides on a third-party server but there are links within some of the pages that refer to an hard-coded address pointing to a static IP (assigned by ISP) hosted on a private local machine.
This is all well and good with the router at the private location, using port-forwarding, etc. But what if someone using a wireless laptop signs on to the domain from within the LAN of that router? Then the hard-coded address points to the WAN of the router...this does not work. The router requires use of a local subnet address.
Please note that the static IP address is not associated with a domain name and may not ever be.
The router is a NETGEAR MR814v2 attached to the Internet via a Paradyne ADSL modem setup as a bridge.
I would have thought that this situation would not be particularly unique and that there may even be a "name" for such a router "feature". Again, I'm not a networking person so this could all be bogus anyway.