求教怎么用C#驱动以SSL方式连接Mongo

[焰火阑珊]

楼主小白，以前没有用SSL，最近用了华为云，他们的数据库默认SSL，给了一个ca.crt的证书，现在想用C#的MongoDB Driver（2.7.0）去连接，看了半天文档，写了下面的代码，但是连接不上，求教各位大神应该怎么改啊？MongoDB版本3.4

            var cert = new X509Certificate2(File.ReadAllBytes("ca.crt"), "password");    //password是数据库的密码，是这么用吗？
            var settings = new MongoClientSettings
            {
                Server = new MongoServerAddress("x.x.x.x", 8635),
                Credential = MongoCredential.CreateCredential("mydatabase", "rwuser", "password"),
                SslSettings = new SslSettings
                {
                    ClientCertificates = new[] { cert },
                },
                UseSsl = true
            };
            MongoClient client = new MongoClient(settings);            
            IMongoDatabase db = client.GetDatabase("mydatabase");
            try
            {
                var collection = db.GetCollection<Admin>("Admin");
                var doc = collection.Find(s => s.Username == "admin").FirstOrDefault();     //程序卡在这一步不走了
                Console.WriteLine(doc.Username);
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }