Something is not set properly.
1. Firewall – Check your firewalls to make sure that the port is not being blocked.
2. Verify that you are putting in the correct information IP address, Port, Service_name
3. Perform a TNSPING
If the ping command succeeds, than it might be a firewall problem.
Typically, when you connect to an Oracle listener (default port is 1521), a new process is spawned/thread created which listens on a different port.
This port is sent back to the client, and the client tries to make a TCP connection to the new oracle process/thread.
So apart from adding the lsnrctl to the firewall rules, you should also add the oracle process to the firewall rule.
The port given back to the client can range anywhere from 1024 to 65535.
Windows users might have a look at the USE_SHARED_SOCKET = TRUE variable you can set in the registry ( HKEY_LOCAL_MACHINESOFTWAREORACLE)
Also see this question.