503 Service Unavailable

Behind our firewall we are getting a "503 service unavailable error, The
requested method is not allowed on this scheme type". This happend on a
link that is using https using port 8490 instead of port 443. The url we
are getting this error is
https://signin.dishmail.net:8490/jar-interfaces/mail. I have brought down
the filters but still had the problem. The prime url is www.dishmail.net
then clicked on the link for email login. All other requests for HTTPS are
using port 443 and they work fine.

Specifics about the server.
novell server 6.5.4
NBM 3.8.4

Seems that the problem is https using a non standard port and the NBM
firewall does not respond on port 8490.