Logstash has stopped processing logs suddenly

Hi Everyone,
My logstash stopped processing logs all of sudden when i checked in kibana one day.
I did not make any changes in any config and it was working earlier from past one year.
Now it is giving below error

Attempted to send a bulk request to elasticsearch' but Elasticsearch appears to be unreachable or down! {:error_message
=>"Elasticsearch Unreachable:

[Manticore::SocketException] Connection reset", :class=>"LogStash::Outputs::ElasticSearch::HttpClient::Pool::HostUnreachableError",
:will_retry_in_seconds=>2}
[ERROR][logstash.outputs.elasticsearch] Attempted to send a bulk request to elasticsearch, but no there are no living connections in the connection pool. Perha
ps Elasticsearch is unreachable or down? {:error_message=>"No Available connections", :class=>"LogStash::Outputs::ElasticSearch::HttpClient::Pool::NoConnectionAvailableError", :will_re
try_in_seconds=>2}.

My logstash is running on a solaris server and elastic search and kibana both are running on same ec2 server.
When i telnet elastic search from logstash server it is successful.
I have not made any changes in configuration.
When i start logstash it creates index once ,parse some logs and again it starts giving same error.
If it is a network side issue then i will have to give a solid proof(logs) to my network team that it is happening because of network but i do not have idea about network side as how to check whether it is network issue or something else.
When i run logstash and elastic search both on same ec2 server.it was running smoothly on that server.
Any help would be grateful.
Thanks in advance.

Please can anyone help me!!