Returning to the original question/error message:
When the IS starts to poll for broker, this means that the connection between IS and Broker has been lost.
As soon as the polling is able to connect to the Broker again, the connection is re-established and the polling stops.
So you should check for timeouts, firewall-clearances and similar issues to work around this problem.
#webMethods#Universal-Messaging-Broker#Integration-Server-and-ESB#broker