When you search for the error returned (ERRORCODE=-4222, SQLSTATE=08001) the issue seems to be a network error preventing the connection.
See: https://stackoverflow.com/questions/16019923/sometimes-cannot-connect-to-a-remote-db2-database
and: https://developer.ibm.com/answers/questions/246094/db2-connection-problem-in-websphere-liberty/
The last link suggest to try to connect on ip rather than name to cirumvent dns issues.
Maybe this will help you in finding a solution.