The following error occurs when trying to connect to Oracle database:
ORA-12547 : TNS lost contact
Client was blocked to connect to the database based on their IP address or hostname by using the parameter below in the SQLNET.ORA file of the Database Server.
tcp.validnode_checking = YES
Change the parameter below to NO in the SQLNET.ORA file of the Database Server to turn off the blocking.
tcp.validnode_checking = NO
NOTE: This will turn off some security features on the database, check with an Oracle DBA to consult the best workaround for the issue.
