Should work on any port but WHY did you use 443, this is SSL for all web browsers! If you need a low end port that useable in mixed windows and linux enviroments, use port 22, SSH as I know few folks using SSH on windows short of putty.
Sounds like V3 check for listen vs open port of V2, go back to V2 if it works for you as thats an issue I cant fault them for in V3. IE uses and list both. I would have guess that you would have been behind a proxy server if it that tight of a network. I will check that out though on my test system just to know.