我们有一个ElasticSearch服务在两个节点上作为集群运行。没有身份验证，它工作正常。指向单个节点也工作正常。但是，当我们使用ConnectionPool运行时，它抛出以下错误。尝试使用SniffingConnectionPool和StaticConnectionPool。两者都没有帮助。我们使用Elasticsearch.Net和Nest版本7.0。

# FailureReason: MaxRetriesReached while attempting PUT on http://ely-es-2-perf.westindia.cloudapp.azure.com:9200/user_profile/_doc/2e18d331-9734-4915-b7cd-4893a270b52c
# Audit trail of this API call:
# Request:
<Request stream not captured or already read to completion by serializer. Set DisableDirectStreaming() on ConnectionSettings to force it to be set on the response.>
# Response:
<Response stream not captured or already read to completion by serializer. Set DisableDirectStreaming() on ConnectionSettings to force it to be set on the response.>
# Inner Exception: One or more errors occurred. (Failed to ping the specified node.) (Failed to ping the specified node.)
System.AggregateException: One or more errors occurred. (Failed to ping the specified node.) (Failed to ping the specified node.)
 ---> Elasticsearch.Net.PipelineException: Failed to ping the specified node.
 ---> Elasticsearch.Net.PipelineException: An error occurred trying to read the response from the specified node.
   at Elasticsearch.Net.RequestPipeline.PingAsync(Node node, CancellationToken cancellationToken)
   --- End of inner exception stack trace ---
   at Elasticsearch.Net.RequestPipeline.PingAsync(Node node, CancellationToken cancellationToken)
   at Elasticsearch.Net.Transport`1.PingAsync(IRequestPipeline pipeline, Node node, CancellationToken cancellationToken)
   at Elasticsearch.Net.Transport`1.PingAsync(IRequestPipeline pipeline, Node node, CancellationToken cancellationToken)
   at Elasticsearch.Net.Transport`1.RequestAsync[TResponse](HttpMethod method, String path, CancellationToken cancellationToken, PostData data, IRequestParameters requestParameters)
   --- End of inner exception stack trace ---
 ---> (Inner Exception #1) Elasticsearch.Net.PipelineException: Failed to ping the specified node.
 ---> Elasticsearch.Net.PipelineException: An error occurred trying to read the response from the specified node.
   at Elasticsearch.Net.RequestPipeline.PingAsync(Node node, CancellationToken cancellationToken)
   --- End of inner exception stack trace ---
   at Elasticsearch.Net.RequestPipeline.PingAsync(Node node, CancellationToken cancellationToken)
   at Elasticsearch.Net.Transport`1.PingAsync(IRequestPipeline pipeline, Node node, CancellationToken cancellationToken)
   at Elasticsearch.Net.Transport`1.PingAsync(IRequestPipeline pipeline, Node node, CancellationToken cancellationToken)
   at Elasticsearch.Net.Transport`1.RequestAsync[TResponse](HttpMethod method, String path, CancellationToken cancellationToken, PostData data, IRequestParameters requestParameters)<---

# Exception:
Elasticsearch.Net.ElasticsearchClientException: Maximum number of retries reached, failed over to all the known alive nodes before failing. Call: Status code 504 from: HEAD /
 ---> System.AggregateException: One or more errors occurred. (Failed to ping the specified node.) (Failed to ping the specified node.)
 ---> Elasticsearch.Net.PipelineException: Failed to ping the specified node.
 ---> Elasticsearch.Net.PipelineException: An error occurred trying to read the response from the specified node.
   at Elasticsearch.Net.RequestPipeline.PingAsync(Node node, CancellationToken cancellationToken)
   --- End of inner exception stack trace ---
   at Elasticsearch.Net.RequestPipeline.PingAsync(Node node, CancellationToken cancellationToken)
   at Elasticsearch.Net.Transport`1.PingAsync(IRequestPipeline pipeline, Node node, CancellationToken cancellationToken)
   at Elasticsearch.Net.Transport`1.PingAsync(IRequestPipeline pipeline, Node node, CancellationToken cancellationToken)
   at Elasticsearch.Net.Transport`1.RequestAsync[TResponse](HttpMethod method, String path, CancellationToken cancellationToken, PostData data, IRequestParameters requestParameters)
   --- End of inner exception stack trace ---
 ---> (Inner Exception #1) Elasticsearch.Net.PipelineException: Failed to ping the specified node.
 ---> Elasticsearch.Net.PipelineException: An error occurred trying to read the response from the specified node.
   at Elasticsearch.Net.RequestPipeline.PingAsync(Node node, CancellationToken cancellationToken)
   --- End of inner exception stack trace ---
   at Elasticsearch.Net.RequestPipeline.PingAsync(Node node, CancellationToken cancellationToken)
   at Elasticsearch.Net.Transport`1.PingAsync(IRequestPipeline pipeline, Node node, CancellationToken cancellationToken)
   at Elasticsearch.Net.Transport`1.PingAsync(IRequestPipeline pipeline, Node node, CancellationToken cancellationToken)
   at Elasticsearch.Net.Transport`1.RequestAsync[TResponse](HttpMethod method, String path, CancellationToken cancellationToken, PostData data, IRequestParameters requestParameters)<---

   --- End of inner exception stack trace ---

我方代码

var uris = new[]
{
    new Uri(_configuration["ElasticAPI1"]),
    new Uri(_configuration["ElasticAPI2"])
};
var connectionPool = new SniffingConnectionPool(uris);
ConnectionSettings settings = new ConnectionSettings(connectionPool).BasicAuthentication(_configuration["ES.Name"], _configuration["ES.Password"]);
ElasticClient client = new ElasticClient(settings);
settings.DefaultIndex(indexname);

//Add data
var response = await client.IndexAsync<Model>(model, null).ConfigureAwait(false);

**编辑：**以前没有设置身份验证时，相同的代码可以工作。在SniffingConnectionPool中工作正常。