Wake-on-LAN working intermittently

Nathan_85

Commendable
Aug 22, 2016
1
0
1,510
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Good evening all,

I'm trying to set my PC up for WOL. I know it is a source of perpetual problems, but I feel like I am oh so close.

I have everything configured, after trawling through the many help sites and manuals out there. My LAN card is set to accept magic packets in BIOS and device manager, port is forwarded (and confirmed open by an external application), I can receive external WOL packets sent from my phone using data connection, so definitely coming via WAN. I'm using a sniffer which picks up the packets every time when my PC is turned on.

When I switch it off however, it only works every so often and I can't work out why. It has woken the PC up from shutdown a few times, again using my phone on data, so I know the packet makes it through, but it won't work reliably enough to actually make use of.

I've seen talk of the network adaptor power management options in device manager, but I've tried both enabling and disabling the "Allow the computer to turn this device off to save power" checkbox. If I disable this then the option to allow it to wake the PC greys out anyway.

I'd be really grateful if anyone has any pearls of wisdom.
 
There are strange issues with bios because microsoft made a mess and defined their own sleep states. WoL is not OS dependent but you need to make sure the other bios things are off.

I am surprised if you have searched on this issue you did not find out why you can't really do it with most routers. There really is not such thing as Wake on WAN. Very technically it should not work sending IP data to some port. There are no IP or port numbers or anything in the WoL. The packet is suppose to be sent to the broadcast mac and contain the mac to wake in a special pattern. Some pc accept data sent to the pc mac address and ignore the extra stuff in the packets. It really depends how strict the bios is to the standard it does not work on all pc.

The reason it works for a while and then fails is you are getting ARP and mac timeouts. When the ARP entry in the router times out and a packet comes in it is mapped to the internal IP correctly but the router does not know what mac to send it to. It issues a ARP but since the PC is off it does not respond. The router then drops the packet. There is also the problem of mac time out in the switch. Since the PC does not send any data while it is asleep the switch will timeout the mac table entries.

You can't fix this on most consumer routers because you can not set the ARP timer or set fixed arp entries.
 

BuddhaSkoota

Admirable
Aug 16, 2014
1,415
0
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I believe most TP-Links have an "IP & MAC Binding" feature, if the OP is fortunate enough to have one. I've used it for WoL from outside my LAN, but not often enough to know if it's 100% reliable. May be something for the OP to look into, or to find if his own router supports binding.

 

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