If you are at all interested in Wake-On-LAN (WOL), read this

I've seen a number of discussions of people being frustrated with getting WOL working on a system. After setting up quite a few systems with WOL I thought that I finally had a handle on this but I ran into a system that was just stumping me today. I finally made a discovery and a connection that I have never seen documented anywhere and I thought that I would just share.

So, I have seen systems that work in two different ways:

1) Some system will allow WOL when the system is shutdown, but not from sleep or hibernate.
2) Some are the opposite: they will allow WOL from sleep or hibernate, but not when shutdown.

Got a new mini PC today and in the process of troubleshooting I had a breakthrough.

I've long known that Fast Startup can interfere with WOL so I always turn it off. But on my new system it was the opposite. WOL would work only if Fast Startup was ENABLED.

Almost instantly, it hit me like a clap of thunder, and I now understand exactly why Fast Startup affects WOL.

Enabling or disabling Fast Startup alters the shutdown behavior of the system. If you ENABLE Fast Startup and then shutdown the system, you are NOT really doing a standard shutdown. You are doing a modified hibernation. As a result, if you have a system that only wants to do WOL when in sleep or hibernate, enabling Fast Startup will allow that system to do a WOL even when you do a shutdown (because you have not really shutdown).

So, if you are driving yourself nuts with WOL and you have all the correct BIOS settings and the settings for the Ethernet adapter all look right and it still won't work, just try toggling Fast Startup. On some systems, like mine, this may work opposite to what you expect, and you may actually need to ENABLE Fast Startup rather than disable it.

Thanks for sharing!
I guess if you have already deleted or stopped Hibernation file, your up a creek without a paddle right?
I never use hibernation but, sometimes I will put the notebook in sleep mode for a few hrs. It won't go to real sleep
right away. You see, on this notebook, I have a MUX switch and I have it on GPU all the time. When I do use sleep mode,
I see that the GPU light (orange) will stay on for sometime before it reverts back to a white lite ( iGPU) so, why??

Hmmm. I think disabling Fast Startup, then disabling hibernation, rebooting, and then re-enabling hibernation should force Windows to recreate hiberfil.sys. It's ben a long time since I mucked around with hiberfil.sys, though, so I'm not 100% sure that an OS level disable and then enable will recreate hiberfil.sys. I know it used to ...back in the days of Windows 7 (?) lol.

The reboot may not be necessary, but it won't hurt anything.

hsehestedt said:

Enabling or disabling Fast Startup alters the shutdown behavior of the system. If you ENABLE Fast Startup and then shutdown the system, you are NOT really doing a standard shutdown. You are doing a modified hibernation. As a result, if you have a system that only wants to do WOL when in sleep or hibernate, enabling Fast Startup will allow that system to do a WOL even when you do a shutdown (because you have not really shutdown).

Click to expand...

So, what you're saying, then, is that if a system will support WoL / accepts the magic packets and wakes up from them, but not when shut down, it's because Fast Startup is disabled?

I can get behind that. But then, if Fast Startup is enabled, and thus should also reverse when WoL works (yes on shut down, no on Standby / hibernate), what is the rationale for this part being logical?

Also - would this have any effect?

Flashorn said:

I guess if you have already deleted or stopped Hibernation file, your up a creek without a paddle right?

Click to expand...

The hibernation file gets recreated on the fly. This is one of the reasons that disk imaging software simply skips certain files like the hibernation and page files. They are basically considered "disposable" files so there is no sense in even backing them up.

johnlgalt said:

So, what you're saying, then, is that if a system will support WoL / accepts the magic packets and wakes up from them, but not when shut down, it's because Fast Startup is disabled?

I can get behind that. But then, if Fast Startup is enabled, and thus should also reverse when WoL works (yes on shut down, no on Standby / hibernate), what is the rationale for this part being logical?

Also - would this have any effect?

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Click to expand...

I can't say conclusively that every single system is going to behave the same way, but here is another way of looking at this:

If Fast Startup IS enabled, then when you perform a shutdown, you are really performing a modified hibernation.
If Fast Startup is NOT enabled, then a shutdown behaves normally, and you are really doing a shutdown.

As a result, if your system is capable of WOL from a hibernated state, then it should also be able to wake from a shutdown IF Fast Startup is enabled because what you are really doing is a modified hibernation. In fact, this is the reason why Fast Startup cannot be enabled on systems that are not capable of hibernation.

Does that make sense?

Well, yes, but this is what is confusing the matter:

hsehestedt said:

So, I have seen systems that work in two different ways:

1) Some system will allow WOL when the system is shutdown, but not from sleep or hibernate.

Click to expand...

That is still bugging me. If it works when shutdown, meaning it is working because of hibernation, then why doesn't it work when it is in hibernation directly?

johnlgalt said:

Well, yes, but this is what is confusing the matter:



That is still bugging me. If it works when shutdown, meaning it is working because of hibernation, then why doesn't it work when it is in hibernation directly?

Click to expand...

Let's take Fast Startup out of the equation entirely. Assume that it is disabled. On some systems the behavior is that WOL will only work with the system shut down. On others, WOL will only work if in hibernation or sleep. Put another way, different systems behave differently.

Now let's add Fast Startup back into the equation.

If you have a system that requires the system to be shut down for WOL to work, then WOL will not work if Fast Startup is enabled.

If you have a system where WOL only works in sleep or hibernation, you can make it work from a shutdown state be turning on Fast startup.

Yes, it's confusing, and that is the point! I've dealt with WOL many times in the past, but it was yesterday when I was setting up a brand new Mini PC that it all suddenly made sense to me. The specs said that this system supports WOL, but there is not a single setting in the BIOS related to WOL, meaning that only Windows settings will affect the behavior. Most systems that I have dealt with want the system to be shut down before WOL will work and there are tons of articles out there that note Fast Startup being on interferes with WOL but they don't say why. Now I get it. It is because when you enable Fast Startup you enter hibernation, not shut down. With this Mini PC I figured out pretty quickly that WOL only worked from hibernation or sleep. But I was experimenting with clean installs of Windows on this machine and forgot to turn off Fast Startup and suddenly WOL worked! I knew that the BIOS has no WOL related settings so all I had to do was figure out what was different in Windows. Almost the instant that I saw that Fast Startup was the only difference it instantly made sense to me because I knew how Fast Startup works and what the implication was.

EDIT: The way to test this is this - Disable Fast Startup. Does WOL on your system now work from sleep? Does it work from hibernation? Does it work when shutdown? You now know what the native behavior is without Fast Startup involved. From there it is easy to predict what would happen if you enable Fast Startup.

Lol confusing it is. But it also makes more sense now.

I have a question pls.
Didn't we have an entry in the shutdown options that also stated to Hibernate at some point.
I don't have that now. Do any of you have it listed?

Try this:

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