Laravel connect to sqlserv RDS

I am trying to connect to a sql server RDS instance from my ubuntu EC2 using Laravel. But I'm always getting this error:

PDOException (20002) 
SQLSTATE[01002] Adaptive Server connection failed (severity 9)

I have added a security group that opens all traffic to the DB just to test the connection but still no luck.

My config looks like:

'sqlsrv' => array(
    'driver'   => 'sqlsrv',
    'host'     => 'mssql.afdafaws.ap-northeast-1.rds.amazonaws.com',
    'database' => 'database',
    'username' => 'username',
    'password' => 'password',
    'prefix'   => '',
),