Wake on LAN stopped working

[enjay]

I have a couple of PCs (curiously next-door to each other) which have stopped responding to the wake-on-lan signals in the morning. I have tried putting them on a different switch, however this had no effect. The PCs are otherwise working fine. Can anyone suggest what could be causing this?

[SYNACK]

Have you checked in the BIOS of the machines and in the Windows Driver options that WOL/Magic packet is still enabled. Some random update or power fluctuation could have reset the bit that disables it.

[sparkeh]

Are they being shutdown gracefully?

WOL won't always work if they have been shut down by holding the power button down (or similar).

Discovered this one myself when I had a similar problem with a machine that wouldnt turn on in the morning. Turns out a teacher was turning the PC off that the wall and then turning the switch back on.

[Domino]

also how often are you scavenging dns records and what are you using to wake them?

I know some thrid-party apps can be confused by stale DNS records and computers with DHCP assigned IP addresses.

Maybe a flushDNS on the workstation?

[enjay]

Thanks for the responses, everyone; to answer the questions:

As far as I know, they are being shut down gracefully (although I've left before they turn off, so I've not actually watched them doing it).

The BIOS is still set up as I would expect, with wake on LAN enabled.

I'm using mc-wol.exe, which goes by MAC address of the NIC so I don't think DNS scavenging would make a difference.

[SYNACK]

You might want to test it with different network cards in as the built in ones may be damaged slightly and not working properly in their low power state.

[gwendes]

Exactly the same problem here but on about 15/25 computers - happened suddenly a few weeks ago... sorry I can't be of any help, just know you're not alone!

[SYNACK]

For both of you I would recommend installing a copy of wireshark on one of the offending machines and set it capturing. Then with the offending machine still running send the WOL command.

If you see it come in on the capture then you know that it has to be directly related to the machine.

I have some machines that require the WOL enable flag to be set in the network cards Windows options as it does not pay attention to the BIOS setting. This may be another thing to look into.

[enjay]

I have some machines that require the WOL enable flag to be set in the network cards Windows options as it does not pay attention to the BIOS setting. This may be another thing to look into.

Identical machines wake fine with the BIOS setting enabled, even on the same switch as the affected ones. I may try the packet trace though, as that would be worth seeing...