Using IWP with a reverse proxy server

I am trying to setup a FMSA9 server that will be accessed via a reverse proxy server. The proxy server is working properly however I am having a problem where FM IWP is returning a the domain name of the local machine not the name of the originating domain.

Example:

Originating Domain URL = http://fmexample.com/fmi/iwp/cgi?-db=MyDatabase&-loadframes

FileMaker server issues redirects using the domain name or IP address passed to it by the reverse proxy.

For instance, with the reverse proxy set to pass requests for fmexample.com to server 10.0.1.100 when the FM server issues a redirect it returns the following URL:

http://10.0.1.100/fmi/iwp/res/iwp_auth.html

If I set the reverse proxy to pass requests for fmexample.com to server "fmexample" (the name of my FMSA9 machine) when the FM server issues a redirect it returns the following URL:

http://fmexample.local/fmi/iwp/res/iwp_auth.html

The proper return URL should be: http://fmexample.com/fmi/iwp/res/iwp_auth.html

I need to a way to make the FM Server think that its name is fmexample.com not fmexample.local.