Standby Server>rman TARGET sys/password@primarydb

Recovery Manager: Release 19.0.0.0.0 - Production on Fri Aug 21 09:20:52 2020
Version 19.7.0.0.0

Copyright (c) 1982, 2019, Oracle and/or its affiliates. All rights reserved.

RMAN-00571: ===========================================================
RMAN-00569: =========
ERROR MESSAGE STACK FOLLOWS
=========
RMAN-00571: ===========================================================
RMAN-00554: initialization of internal recovery manager package failed
RMAN-04005: error from target database:
ORA-12170: TNS:Connect timeout occurred

Standby Server>tnsping primarydb

TNS Ping Utility for Solaris: Version 19.0.0.0.0 - Production on 21-AUG-2020 09:55:55

Copyright (c) 1997, 2019, Oracle.  All rights reserved.

Used parameter files:
/u01/app/ora19c/network/admin/sqlnet.ora


Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = primarydb)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = primarydb)))
OK (0 msec)

Standby Server>more listener.ora
SID_LIST_LISTENER =
(SID_LIST =
  (SID_DESC =
   (GLOBAL_DBNAME = primarydb)
   (ORACLE_HOME = /u01/app/ora19c)
   (SID_NAME = primarydb)
  )
  (SID_DESC =
   (GLOBAL_DBNAME = standbydb)
   (ORACLE_HOME = /u01/app/ora19c)
   (SID_NAME = standbydb)
  )
)
LISTENER =
(DESCRIPTION_LIST =
  (DESCRIPTION =
   (ADDRESS = (PROTOCOL = TCP)(HOST = standby)(PORT = 1521))
  )
  (DESCRIPTION =
   (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
  )
)




Standby Server>more tnsnames.ora
standbydb =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = standby)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = standbydb)
    )
  )

primarydb =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = primary)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = primarydb)
    )
  )

-bash-5.0$ more tnsnames.ora
# tnsnames.ora Network Configuration File: /u01/app/ora19c/network/admin/tnsnames.ora
# Generated by Oracle configuration tools.

primarydb =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = primary)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = primarydb)
    )
  )

standbydb =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = standby)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = standbydb)
    )
  )