You don't indicate what the result is of the IP address (not name) test is WITHOUT the port #.
If it does work with the IP address without the port specified (so defaulting to port 80) but it fails with the DNS name on port 80, that would point to a problem in the DNS somewhere.
This statement can not be true:
The technician reassures us that the address coming in on port 80, 'http://test21.hostcompany.net/folder/orderpage.html', is coming out of the firewall as 'http://test21.hostcompany.net/folder/orderpage.html' port 591 to the server computer.
What would come out of the firewall / router would be: http://<ip address or DNS name of your FMS machine>:591/folder/orderpage.html. Otherwise the firewall setup would not have "translated" anything.
On the new firewall (not Cisco)...[all configurations are now failing]
(on the above configuration the 'test21.' is added because 'hostcompany.net' routes to a web hosting company [setup while I was away from this company]. My original setup [see below] had the main domain hosted at the same location. I did a trace route on the 'test21.hostco...' and the main domain 'hostcompany.net'- both appear to be routing properly, 'test21.hostco...' to this location, and the main domain routing to the hosting company in a different state.) Could it somehow be related to the addition of the 'test21.'
On the old firewall [my original setup] (Cisco)...
I'm assuming that the fake IP address in your test is the public ip address assgined by your ISP? If that's so then it's not a DNS issue like the subdomain addition, it's the firewall that is not set up correctly. Use the firewall logs to confirm that the traffic actually reaches the firewall. From there it's back to the guy that configured the firewall
Yes those are the public IP's I speak of... (oops, ending preposition!) Thanks Wim, I will request a log printout, although the Trace Route showed the request going to the facility first, then bouncing wildly around the map.