When I test it on my machine using the Visual Studio web server which launches the site on a random port, it works fine, the port is always included in the url.
Are you proxying it to another port on the web server or really running and accessing it on that port?
Might I ask why use an non standard port in the first place? Often I see people doing that because they have another site running on port 80 on the same machine and ip address, but there are better alternatives such as using host headers to run multiple sites on the same ip address and using standard ports.
Best,
Joe