client.assumeRole授权访问出错

报错内容：

{
    "message": "getaddrinfo ENOTFOUND sts.aliyuncs.com, POST https://sts.aliyuncs.com -1 (connected: false, keepalive socket: false, socketHandledRequests: 1, socketHandledResponses: 0)\nheaders: {}"
}

环境：本地localhost

后端： koa

代码片段：

const sts = async (ctx) => {
    const conf = JSON.parse(fs.readFileSync(path.resolve(__dirname, './config.json')));
    let policy;
    if (conf.PolicyFile) {
      policy = fs.readFileSync(path.resolve(__dirname, conf.PolicyFile)).toString('utf-8');
    }
    const client = new STS({
        accessKeyId: conf.AccessKeyId,
        accessKeySecret: conf.AccessKeySecret
    });
    try {
        console.log(conf);
        const result = await client.assumeRole(conf.RoleArn, policy, conf.TokenExpireTime);
        ctx.set('Access-Control-Allow-Origin', '*');
        ctx.set('Access-Control-Allow-METHOD', 'GET');
        ctx.body = {
            code: 0,
            message: '请求sts签名成功',
            bucket,
            region,
            accessKeyId: result.credentials.AccessKeyId,
            accessKeySecret: result.credentials.AccessKeySecret,
            securityToken: result.credentials.SecurityToken,
            expiration: result.credentials.Expiration
        };
    } catch (e) {
        ctx.body = utils.errorHandle(e.message || '');
    }
};

程序前几次没有报这个错，可以顺利上传图片，后面就一直报这个错。望各路大神帮忙！