David,
Sounds like there is a HOST name issue here. What happens if you go directly to http://domino-file.rfdinc.com/ . . .? I suspect it would work. If so, then DXLPeek may be using the session to get the hostname instead of depending on the CGI variables.
I realize this causes a problem for you, but I'm not sure if it's really a DXLPeek bug. We could probably tweak DXLPeek to figure out if the server's host name differs from the requested host and either report it to the user or maybe substitute it. Do you see this a big problem?
Thanks,
Ian