Problem:

In initial connection, if one of the seed mongo processes is down, the connection won't be established. a machine/process can be down for a long time, this means no new connection can be established during this time, this defeats the purpose of High Availability of a replication set.

Expected Result:

As long as one of the seed process is working, connection should be established.

Note:

Not repro in NodeJS driver. so it's C# driver's issue.

Error:

at MongoDB.Driver.Core.Servers.ClusterableServer.<HeartbeatAsync>d__d.MoveNext()" }, { ServerId: "

{ ClusterId : 1, EndPoint : "Unspecified/vmpri0521e.westus.cloudapp.azure.com:27000" }

", EndPoint: "Unspecified/vmpri0521e.westus.cloudapp.azure.com:27000", State: "Disconnected", Type: "Unknown", HeartbeatException: "MongoDB.Driver.MongoConnectionException: An exception occurred while opening a connection to the server. ---> System.Net.Sockets.SocketException: No connection could be made because the target machine actively refused it 191.236.92.13:27000