its a generic issue. Its not related to port in firewall.
reinstall the jinitiator and recheck the issue, if not updated to jre
If you are using jinitiator then use firefox 2.0 version to open the forms.
Disable the xxfilter option in IE settings and retest.
Additionally you may refer the following Note as well , if it can help
After Implementing Forms Listener Servlet setup, FRM-92050: Failed to connect to the Server: /forms/formservlet:-1 Error When Launching Forms (Doc ID 374205.1)