Trying to connect to Oracle DB using a JDBC step in DevTest, gives the below error.
java.sql.SQLException: Io exception: The Network Adapter could not establish the connection
We tried to Telnet to the host and port Oracle DB was running, and got an error.
telnet <host> 1521
"java.sql.SQLException: IO Error: The Network Adapter could not establish the connection" - This error message is Oracle's way of saying either 'Connection refused' or 'Connection timeout' or 'no route to host' or 'unknown host'.
It might be that there is no route to the host, nothing listening at the IP:port you specified, or there is a firewall in the way. And that includes a possible Windows firewall on the server host itself.
Work with your Network team to resolve the Oracle issue.