Oracle Database Discussions

After installing Oracle Database 19c on my Windows Server, I created a database with the following tnsnames.ora (I customized the listening port).

DBNAME =
    (DESCRIPTION =
        (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 3496))
            (CONNECT_DATA =
                (SERVER = SHARED)
                (SERVICE_NAME = dbname.domainname.com)
        )
    )

LISTENER_DBNAME = (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 3496))

When connecting to the database with the SYS user I can connect without problem :

sqlplus SYS/"sysTstPwd"@DBNAME as SYSDBA

for creating my USER I do this :

--Create USER only works if the container is set to PDB
alter session set container=PDB;


CREATE USER TSTUSER IDENTIFIED BY "tstPwd99";

grant connect to TSTUSER;
grant resource to TSTUSER;

Then I try to connect with my new USER to the database :

sqlplus TSTUSER/"tstPwd99"@DBNAME

And I get the error :

ERROR:
ORA-01017: invalid username/password ; connection refused

Could anyone help with this?

Best Regards,

Thomas