APEX

I have a situation where I have a fully functional APEX 2.2 (with 10gR2 db) environment, but I cannot access APEX through my router/firewall. This means I'm up and running within my intranet, but I cannot expose APEX to the Internet. I've opened the Apache Port in the firewall, and I know this hole is working. To explain this perplexing situation assume:

http://mywebserver.com (Internet routable address)
http://mywebserver (Intranet routable address of same host)

My APEX handler <Location> in marvel.conf is "/apex"

Here are the scenarios that work and fail:

intranet client using http://mywebserver/ (works)
intranet client using http://mywebserver/apex/ (works)
internet client using http://mywebserver.com/ (works)
internet client using http://mywebserver.com/ (fails)

The failure results in the dreaded HTTP 404. There is NO logging information in the Apache log - so it isn't even getting handled. I don't understand how the static pages can be served through the firewall but not APEX pages. As I said APEX is working fine, but there are some firewall settings I am missing...

Any advice welcome.

P.S. I've tried IE6, IE7 and Firefox and verified the behavior consistently from multiple Internet client locations.