How to check the connection timeout in Oracle

You can try using:

ps -ef | grep -v grep | grep ora_pr

Or if data guard is in use:

ps -ef | grep -v grep | grep ora_rsm

First of all check whether your pluggable database is opened or not.

SQL> select name, open_mode from v$pdbs where name='PDBORCL';

If it is in mounted mode then,

SQL> alter pluggable database pdborcl open;

Now on SQL Developer Create new connection as,

Connection Name: demo-pdborcl

Username: demo

Password: *****

Connection Type: Basic(If you wish to use TNS connection type you have to create TNS Network Alias in client side.)

Hostname: ip/dns

Port: 1521

SID: (If you use SID like 'ORCL' you will be connected to root container, therefore use Service name instead of SID)

Service name: (You can get your pdb's service name by firing $ lsnrctl serivce, also you can use USE_SID_AS_SERVICE_listener parameter on $ORACLE_HOME/network/admin/listner.ora file as USE_SID_AS_SERVICE_listener=on and any given SID will be treated as service name.

Some useful links-