Driver - 2.4.3
MongoDB Community - 3.4.4

Environment:
Server A: MongoDB Standalone server (2 Core 3.5 G RAM) [Windows Server 2012 R2]
Server B: Web App (4 Core 7 G RAM) [Windows Server 2012 R2]

As i was trying out MongoDB and performing Load Test. I was hit with the following 2 types of errors repetitively for 30 seconds and it back to normal.

Error Type 1:
System.TimeoutException: A timeout occured after 30000ms selecting a server using CompositeServerSelector{ Selectors = WritableServerSelector, LatencyLimitingServerSelector

{ AllowedLatencyRange = 00:00:00.0150000 }

}. Client view of cluster state is { ClusterId : "1", ConnectionMode : "Automatic", Type : "Unknown", State : "Disconnected", Servers : [{ ServerId: "

{ ClusterId : 1, EndPoint : "10.0.0.12:27017" }

", EndPoint: "10.0.0.12:27017", State: "Disconnected", Type: "Unknown" }] }.
at MongoDB.Driver.Core.Clusters.Cluster.ThrowTimeoutException(IServerSelector selector, ClusterDescription description)
at MongoDB.Driver.Core.Clusters.Cluster.WaitForDescriptionChangedHelper.HandleCompletedTask(Task completedTask)
at MongoDB.Driver.Core.Clusters.Cluster.WaitForDescriptionChanged(IServerSelector selector, ClusterDescription description, Task descriptionChangedTask, TimeSpan timeout, CancellationToken cancellationToken)
at MongoDB.Driver.Core.Clusters.Cluster.SelectServer(IServerSelector selector, CancellationToken cancellationToken)
at MongoDB.Driver.Core.Bindings.WritableServerBinding.GetWriteChannelSource(CancellationToken cancellationToken)
at MongoDB.Driver.Core.Operations.BulkMixedWriteOperation.Execute(IWriteBinding binding, CancellationToken cancellationToken)
at MongoDB.Driver.OperationExecutor.ExecuteWriteOperation[TResult](IWriteBinding binding, IWriteOperation`1 operation, CancellationToken cancellationToken)
at MongoDB.Driver.MongoCollectionImpl`1.ExecuteWriteOperation[TResult](IWriteOperation`1 operation, CancellationToken cancellationToken)
at MongoDB.Driver.MongoCollectionImpl`1.BulkWrite(IEnumerable`1 requests, BulkWriteOptions options, CancellationToken cancellationToken)
at MongoDB.Driver.MongoCollectionBase`1.InsertOne(TDocument document, InsertOneOptions options, CancellationToken cancellationToken)
at ILT.Data.Agents.MongoDBAgent.Create(Sample sample)
at ILT.Business.TestComponent.TestNoSQLMongoDBMethod()

Error Type 2:
System.TimeoutException: A timeout occured after 30000ms selecting a server using CompositeServerSelector{ Selectors = WritableServerSelector, LatencyLimitingServerSelector

{ AllowedLatencyRange = 00:00:00.0150000 }

}. Client view of cluster state is { ClusterId : "1", ConnectionMode : "Automatic", Type : "Unknown", State : "Disconnected", Servers : [{ ServerId: "

{ ClusterId : 1, EndPoint : "10.0.0.12:27017" }

", EndPoint: "10.0.0.12:27017", State: "Disconnected", Type: "Unknown", HeartbeatException: "MongoDB.Driver.MongoConnectionException: An exception occurred while opening a connection to the server. ---> System.Net.Sockets.SocketException: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond 10.0.0.12:27017
at System.Net.Sockets.Socket.EndConnect(IAsyncResult asyncResult)
at System.Threading.Tasks.TaskFactory`1.FromAsyncCoreLogic(IAsyncResult iar, Func`2 endFunction, Action`1 endAction, Task`1 promise, Boolean requiresSynchronization)
— End of stack trace from previous location where exception was thrown —
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at MongoDB.Driver.Core.Connections.TcpStreamFactory.<ConnectAsync>d__7.MoveNext()
— End of stack trace from previous location where exception was thrown —
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at MongoDB.Driver.Core.Connections.TcpStreamFactory.<CreateStreamAsync>d__4.MoveNext()
— End of stack trace from previous location where exception was thrown —
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at MongoDB.Driver.Core.Connections.BinaryConnection.<OpenHelperAsync>d__48.MoveNext()
— End of inner exception stack trace —
at MongoDB.Driver.Core.Connections.BinaryConnection.<OpenHelperAsync>d__48.MoveNext()
— End of stack trace from previous location where exception was thrown —
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at MongoDB.Driver.Core.Servers.ServerMonitor.<HeartbeatAsync>d__27.MoveNext()" }] }.
at MongoDB.Driver.Core.Clusters.Cluster.ThrowTimeoutException(IServerSelector selector, ClusterDescription description)
at MongoDB.Driver.Core.Clusters.Cluster.WaitForDescriptionChangedHelper.HandleCompletedTask(Task completedTask)
at MongoDB.Driver.Core.Clusters.Cluster.WaitForDescriptionChanged(IServerSelector selector, ClusterDescription description, Task descriptionChangedTask, TimeSpan timeout, CancellationToken cancellationToken)
at MongoDB.Driver.Core.Clusters.Cluster.SelectServer(IServerSelector selector, CancellationToken cancellationToken)
at MongoDB.Driver.Core.Bindings.WritableServerBinding.GetWriteChannelSource(CancellationToken cancellationToken)
at MongoDB.Driver.Core.Operations.BulkMixedWriteOperation.Execute(IWriteBinding binding, CancellationToken cancellationToken)
at MongoDB.Driver.OperationExecutor.ExecuteWriteOperation[TResult](IWriteBinding binding, IWriteOperation`1 operation, CancellationToken cancellationToken)
at MongoDB.Driver.MongoCollectionImpl`1.ExecuteWriteOperation[TResult](IWriteOperation`1 operation, CancellationToken cancellationToken)
at MongoDB.Driver.MongoCollectionImpl`1.BulkWrite(IEnumerable`1 requests, BulkWriteOptions options, CancellationToken cancellationToken)
at MongoDB.Driver.MongoCollectionBase`1.InsertOne(TDocument document, InsertOneOptions options, CancellationToken cancellationToken)
at ILT.Data.Agents.MongoDBAgent.Create(Sample sample)
at ILT.Business.TestComponent.TestNoSQLMongoDBMethod()

This is my Code. No async method used.
private static readonly MongoClient _mongoClient;

static MongoDBAgent()

{ _mongoClient = new MongoClient(ConfigurationManager.ConnectionStrings["MongoDB"].ConnectionString); }

public void Create(Sample sample)

{ var db = _mongoClient.GetDatabase("ILT"); var collection = db.GetCollection<Sample>("Sample"); collection.InsertOne(sample); }

This is my mongodb connectionString.
mongodb://username:password@10.0.0.12:27017/ILT

ILT is the database name.
10.0.0.12 is mongodb standalone local IP address.

After that i tried to simulate again and again but couldn't get back the error. I have attach the log file for your information.