windows 8.1 won't go into sleep mode,

What's missing from this thread is some form of interaction by Microsoft.

I didn't have this problem with either Windows 7 or Windows 8. No hardware changes. Only software change is a supposed UPGRADE to Windows 8.1.

My machine went to sleep properly 3 times last night, it made it through the night. Again went to sleep twice this morning BUT it failed on the 3rd. Shut it down for 10 minutes. After reboot went to sleep properly. Will see how long it lasts if at all.

Anyone out there from Microsoft?

I agree that it's not the physical adapter but rather a network setting/configuration.  When it is disabled or the ethernet cable is unplugged, there's no issues so it is certainly a network issue.

Not an issue with Win 8.0.

I found that after removing the homegroup and un-sharing all folders things seemed to be corrected but after about one day the insomnia was back.  So, there's something else happening.

Brimmichael, I scoured every solution even asking HP support, they suggest cleaning the drive and going to square 1. I told them that is not an option. I have stopped the v6 even going into registry and doing as some suggestion to stop v6. I have disabled the adapter which works, but is not practical. Last evening I disconnected from the home group and I can agree that isn't the solution, but when I started up this morning so far it goes into sleep mode, and I shall see as the day goes on.

The homegroup may not be the solution, but it does clear the problem. I had not problem with 8, until I upgraded to 81. I also had a problem with flashplayer which is another issue.

Andy: I tend to think it is a "Network" issue as opposed to the "adapter" . Have  no proof of this but too many people are having the problem and I doubt we are all sharing the same adapter.

Right now my computer is sleeping but I'm not sure why because I made two changes  (1) was that I left the HomeGroup on all 4 machines and (2) under Power Options I set both display & sleep to "never" shutdown for 2 minutes - rebooted restored default Power Options - shutdown for 2 minutes - rebooted and 30 minutes later was sleeping like a baby.

Completely contrary to advice in other threads the network adapter is set to wake the computer as are mouse and keyboard. Advanced Power Options are also default.

Will give it another 24 hours and report back because I've seen these the insomnia return.

Of course shutting off HomeGroup is NOT a solution and defeats the whole point of having a Windows network. I think Microsoft has to actually put some effort to providing a real solution. I've got 4 machines 2 of which are still on Windows 7 and given the problems I've had with Windows 8.1 I won't be upgrading.

I've also confirmed that it's the adapter.  When I unplug the Ethernet cable there's no problem. 

I also completely removed the homegroup on both PC's.  One being my main PC running win 8.1, the other running win 7.  I unshared all folders on both PC's.  But the no sleeping issue persists.  What's more frustrating is that even after manually putting the Win 8.1 PC to sleep, it continues to be woken up.  So I have to completely power the pc down every time I'm done with it, which is terribly annoying.  As other's are having this issue also, I'm hoping that somebody from Microsoft will determine the proper fix and push an update.  But as Microsoft has yet to address this posting, I have little faith.