ORA-12666: Dedicated server: outbound transport protocol different from inbound
Cause: The protocol specified for an externally-identified outbound connection from a dedicated server (database link) was not the same as that used for the inbound connection. It is not possible for Oracle Net to authenticate a proxy connection that uses a protocol that is different from that which was used for the connection to the dedicated server.
Action: Specify the same protocol in the Oracle Net connect descriptor for the outbound connection as that used for the inbound connection.
Error Type: ORA