Hi,
Sometimes You can get “ORA-12570: TNS:packet reader failure” error.
Details of error are as follows.
ORA-12570: TNS:packet reader failure
Cause: An error occurred during a data receive.
Action: Not normally visible to the user. For further details, turn on tracing and reexecute the operation. If error persists, contact Oracle Customer Support.
This error may be related with the Firewall settings.
To solve this error, Disable the firewall in Windows or Linux reading the following post.
https://ittutorial.org/oracle-linux-firewall-disable/
Do you want to learn more details about RMAN, then read the following articles.
https://ittutorial.org/rman-backup-restore-and-recovery-tutorials-for-beginners-in-the-oracle-database/