Connection fails with ORA-12545 while 'second' server of failover doesn't run when using IP in TN (4322173)

It's possible to successfully connect to the 'first' of the two Databases (2 Server) in failover mode, but when shutting down the first instance it's not possible to connect to the second and getting an ORA-12545.

Specifying the IP addresses in the TNSNAMES.ORA for the 2 Servers, for example:

failover =
(DESCRIPTION =
(ADDRESS =
(PROTOCOL = TCP)
(HOST = 10.20.30.15)
(PORT = 1521)
)
(ADDRESS =
(PROTOCOL = TCP)
(HOST = 10.20.30.18)
(PORT = 1521)
)
(LOAD_BALANCE = yes)
(CONNECT_DATA =
(SERVICE_NAME = failover)
(SERVER = dedicated)
(FAILOVER_MODE =
(TYPE = select)
(METHOD = basic)
(RETRIES = 180)
(DELAY = 5)
)
)
(FAILOVER = yes)
)

So, we have
Server_1 on 10.20.30.15 and
Server_2 on 10.20.30.18.