We are seeing frequent failures of scheduled resfreshes with an error of "The gateway is either offline or could not be reached", but upon (repeated) investigation, there is no apparent problem with the gateway or network connectivity on our end. The next refresh will succeed. The GW shows up as online and "good to go" in Power Bi service.
This is happening with datasets coming from SQL server and from web services. We've tried restarting the GW, upgrading, reinstalling, restarting the server, etc. it makes no difference.
At about the time of the failure, the main log shows a suspicious-looking "[DM.GatewayCore] Async operation ... 1 transitioned into Cancelled state after 300 seconds timeout" and the error log shows several "DM.EnterpriseGateway Error: 1 ... [DM.NetworkCore] Non-gateway network exception encountered in activity scope: System.ServiceModel.CommunicationException: The socket connection has been disposed. ---> System.IO.IOException: The write operation failed, see inner exception. ---> System.ServiceModel.CommunicationException: The socket connection has been disposed. ---> System.ObjectDisposedException: Cannot access a disposed object." errors.
