Can you check /etc/hosts file on the server ?
Also check application.log
Did you apply the OS Library Patch for Oracle HTTP Server (on Oracle Linux 5, RHEL 5, Oracle Linux 6, RHEL 6, Oracle Linux 7 and RHEL 7 only)?
Oracle E-Business Suite Installation and Upgrade Notes Release 12 (12.1.1) for Linux x86-64 (Doc ID 761566.1)
And whats the value of - grep s_webport $CONTEXT_FILE.
Library patch resolved the issue. I thought its a negligible small thing