Exception encountered: A timeout occured after 30000ms selecting a server using CompositeServerSelector{ Selectors = MongoDB.Driver.MongoClient+AreSessionsSupportedServerSelector, LatencyLimitingServerSelector{ AllowedLatencyRange = 00:00:00.0150000 } }. Client view of cluster state is { ClusterId : "2", ConnectionMode : "Automatic", Type : "Unknown", State : "Disconnected", Servers : [{ ServerId: "{ ClusterId : 2, EndPoint : "Unspecified/MYCLUSTERNAME-shard-00-00.34sww.mongodb.net:27017" }", EndPoint: "Unspecified/MYCLUSTERNAME-shard-00-00.34sww.mongodb.net:27017", State: "Disconnected", Type: "Unknown", HeartbeatException: "MongoDB.Driver.MongoConnectionException: An exception occurred while opening a connection to the server. ---> System.Security.Authentication.AuthenticationException: The remote certificate is invalid according to the validation procedure.

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12 | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls;

var settings = new MongoClientSettings
{
    ApplicationName = "iApply",
    ConnectionMode = ConnectionMode.Automatic,
    Server = new MongoServerAddress(clusterSVRHostnmae),
    Credential = MongoCredential.CreateCredential(authDb, username, password),
    Scheme = ConnectionStringScheme.MongoDBPlusSrv,
    UseTls = true,
    GuidRepresentation = GuidRepresentation.CSharpLegacy
};

// settings.SslSettings = new SslSettings
// {
//     CheckCertificateRevocation = true // <= this causes timeout on servers with restricted connectivity!!!
// };

var client = new MongoClient(settings);
var db = client.GetDatabase("databaseName");