Re: Esxi 5.1 host unable to exit standby mode while running wake on lan test case.

Hi...

This issue is described in this KB:

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2012152

However, did you extended time-out on both of vCenter and ESXi host..??
Did you checked your network connection on which you send WOL command..???