The host failed to exit standby mode.
Standby Mode powers off an vSphere host and allows it to be powered back on again through Wake-on-LAN protocol triggered either manually or automatically by vCenter Server.
Do not disconnect a host in standby mode or move it out of the DRS cluster without first powering it on, otherwise vCenter Server is not able to power the host back on.
Power the host on using a different method and then disable VMware DPM on that host until you the issue is resolved.
See the vSphere Resource Management Guide for more information.
Refer to the VMware Online Documentation for more information.