Getting "Ora-12571 TNS:packet writer failure" when optimizing (4242374)

I am getting an "Ora-12571 TNS:packet writer failure" error when trying to optimize a query.

Oracle client is not supported

Upgrade your Oracle client to 9i, 10g, or 11g and follow the steps below to select the newer client:

1. Launch SQL Optimizer.
2. Select a 10g oracle client i the Login sceen in the Installed client section and click on the create button.
3. in SQL rewrite, have a simple select * from dual:
4. Hit the Auto Optimizer link and select the 10g connection.