Java: Getting Error: read ECONNRESET when HTTPD says 200 Ok and code successfully executed till end

Question

A Heavy Request comes to application; deployed in my wildfly server; via HTTPD. It takes 5 minutes to process 800 Records in request. (Application calls 2 servers using Multithreading and concatenate results and send back)

Application run till end:

2022-03-14 15:06:21,545 INFO  [com.gvry.chintugrator.msc.service.ToneConfigurationItemSearchResource] (default task-1) Before Result With Status: 200
2022-03-14 15:06:21,545 INFO  [com.gvry.chintugrator.msc.service.ToneConfigurationItemSearchResource] (default task-1) Before Result With StatusInfo: OK
2022-03-14 15:06:21,545 INFO  [com.gvry.chintugrator.msc.service.ToneConfigurationItemSearchResource] (default task-1) Before Result With ToString: org.jboss.resteasy.specimpl.BuiltResponse@7779817c

@POST
@Produces({ MediaType.APPLICATION_JSON, MediaType.APPLICATION_XML })
@Path("/configuration-items")
public Response searchForConfigurationItems(ConfigurationItemsSearch search) {
 --after 5 to 6 mins
 --log(message and success))
 return Response.ok().entity(new GenericEntity<List<ConfigurationItem>>(configurationItems)
}

But after processing my Postman, ARC and client are getting "Error: read ECONNRESET"

Strange thing is:

HTTPD log says 200 when i hit from both Postman and ARC

net.cosng.integrator.qa.masterdata_access.log:[14/Mar/2022:14:44:33 +0100] 253.110.6.132, 139.316.415.46, 410.0.11.23 (410.0.11.23) masterdata.qa.chintugrator.cosng.net 
"POST //mscbilling/api/search/configuration-items HTTP/1.1" 200 "PostmanRuntime/7.29.0"

HTTPD timeout is 900 seconds and request return in 5-6 minutes

ARC client has following in header.

Postman has following in header:

Then i downloaded Google Chrome ARC plugin and it returns 200 OK but

There is no issue in response json which i print in logs.

Where is the issue is