MongoDB timeout for C # multithreaded operations

The environment:windows server
Mongodb version:4.2
MongoDB.Driver version:2.13.0

When I run mongo in multiple threads concurrently, I’m prompted to timeout the connection, which has been normal until now.

A timeout occurred after 30000ms selecting a server using CompositeServerSelector{ Selectors = MongoDB.Driver.MongoClient+AreSessionsSupportedServerSelector, LatencyLimitingServerSelector{ AllowedLatencyRange = 00:00:00.0150000 }, OperationsCountServerSelector }. Client view of cluster state is { ClusterId : "1", Type : "Unknown", State : "Disconnected", Servers : [{ ServerId: "{ ClusterId : 1, EndPoint : "139.196.115.25:27017" }", EndPoint: "139.196.115.25:27017", ReasonChanged: "ServerInitialDescription", State: "Disconnected", ServerVersion: , TopologyVersion: , Type: "Unknown", LastHeartbeatTimestamp: null, LastUpdateTimestamp: "2021-07-17T01:45:04.8019577Z" }] }.
   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.MongoClient.AreSessionsSupportedAfterServerSelection(CancellationToken cancellationToken)
   at MongoDB.Driver.MongoClient.AreSessionsSupported(CancellationToken cancellationToken)
   at MongoDB.Driver.MongoClient.StartImplicitSession(CancellationToken cancellationToken)
   at MongoDB.Driver.OperationExecutor.StartImplicitSession(CancellationToken cancellationToken)
   at MongoDB.Driver.MongoCollectionImpl`1.UsingImplicitSession[TResult](Func`2 func, CancellationToken cancellationToken)
   at MongoDB.Driver.MongoCollectionImpl`1.BulkWrite(IEnumerable`1 requests, BulkWriteOptions options, CancellationToken cancellationToken)
   at MongoDB.Driver.MongoCollectionBase`1.<>c__DisplayClass68_0.<InsertOne>b__0(IEnumerable`1 requests, BulkWriteOptions bulkWriteOptions)
   at MongoDB.Driver.MongoCollectionBase`1.InsertOne(TDocument document, InsertOneOptions options, Action`2 bulkWrite)
   at MongoDB.Driver.MongoCollectionBase`1.InsertOne(TDocument document, InsertOneOptions options, CancellationToken cancellationToken)