Make sure that the sqlnet.ora file on both the client and the server, available under ORACLE_BASE\ORACLE_HOME\network\admin\sqlnet.ora, has the following entry:
Connect to the Oracle database as SYSDBA.
Create the Windows user as an external user in the Oracle database. Note that the user name must be in upper case.
CREATE USER “OPS$<DOMAIN_NAME>\<USER_NAME>” IDENTIFIED EXTERNALLY;
Grant privileges to the user.
GRANT CONNECT,RESOURCE TO “OPS$<DOMAIN_NAME>\<USER_NAME>”;