InformationAuto-start directs the host to start VM guests when the host is restarted or powered on. In XenServer 6.x, the auto-start functionality was removed from the GUI because it interfered with high availability (HA) and produced unexpected results. The feature can be safely enabled in a standalone host from the command line.
SolutionDisable auto-poweron at the pool level by running this command:
xe pool-param-set uuid=<pool_uuid> other-config:auto_poweron=false
See the article linked below to enable auto_poweron in a standalone host.