Failed to obtain JDBC connection error from TDM Portal Oracle connection profile.

Products

• CA Test Data Manager (Data Finder / Grid Tools)

Issue/Introduction

When testing a connection profile in the TDM Portal to Oracle for the first time, the following error was shown: 
Failed to connect.
The server replied: Failed to obtain JDBC Connection; IO Error: The Network Adaptor could not establish the connection

PORTQRY from the TDM server to the Oracle server showed the port as listening.
ojdbc8.jar had been copied to E:\Program Files\CA\CA Test Data Manager Portal\tomcat\jdbc-drivers

Environment

Release : 4.9

Resolution

Oracle SQL Developer was installed and it was also not able to connect.
The problem was related to a network issue with a firewall and aliases and was difficult to diagnose.
Using Oracle SQL Developer allowed this to be investigated.