'seta' ]; $m = new \MongoDB\Client( 'mongodb://localhost:13000/?replicaSet=seta' ); $m = new \MongoDB\Client( 'mongodb://localhost:13000,localhost:13001', $options ); $m = new \MongoDB\Client( 'mongodb://user:password@localhost:13000/demo', $options ); ?>]]> Add more than one host for seeding (a majority) Don't add the arbiters to the connection string