http 500 error when try to access EBS

Hi

When attempting to access EBS,HTTP 500 occur,the page that input username and password can not be displayed

500 Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request

the issue occur many times recently,by restarting AP and DB,the issue got fix.

During the issue occur

From error log,we can found the error below

[Tue Apr 19 16:09:31 2016] [warn] [client 172.22.226.26] oc4j_socket_recvfull timed out
[Tue Apr 19 16:09:31 2016] [warn] [client 172.20.178.30] oc4j_socket_recvfull timed out
[Tue Apr 19 16:09:31 2016] [error] [client 172.20.178.30] [ecid: 1461053069:10.10.10.138:43450378:0:2952,0] mod_oc4j: request to OC4J atk01.aoert.com:21501 failed: Connect failed