Hi,
Sometimes You can get “TNS-12571: TNS:packet writer failure ” error.
Details of error are as follows.
TNS-12571: TNS:packet writer failure
Cause: An error occurred during a data send.
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 NLS_NCHAR_CHARACTERSET option is set to AL16UTF16.
To solve this error, Change the NLS_NCHAR_CHARACTERSET to UTF8.
Or 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/