Please refer to the below error and causes for a connection timeout error.

Error: 

2020-03-06 11:56:53 pool-1-thread-1 ERROR AEAgentSeqWFHandler:49 - Error fetching sequential workflows

org.apache.http.conn.HttpHostConnectException: Connect to 172.17.137.8:8443 [/172.17.137.8] failed: Connection refused: connect

Causes: