在AWS OpenSearch客户端配置中，需要关闭"verifyHostnames"选项。以下为示例代码：

const OpenSearch = require('opensearch-node');

const opensearchClient = new OpenSearch({
  host: 'your-opensearch-endpoint-url',
  amazonES: {
    region: 'your-region',
    accessKey: 'your-access-key',
    secretKey: 'your-secret-key'
  },
  modifyEndpoint: (endpoint) => {
    // Disable hostname verification
    endpoint.host = endpoint.host.replace('.es.amazonaws.com', '');
    endpoint.protocol = 'https:';
    endpoint.rejectUnauthorized = false;
    return endpoint
  }
});

在配置示例代码中，将"verifyHostnames"选项关闭，即设置"rejectUnauthorized"为false。这允许AWS OpenSearch客户端连接到Elasticsearch服务器，而不需要验证主机名。