Wake on lan pc does not start after a few good wol

dragos2b

Honorable
Apr 8, 2012
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10,510
Hello,
I have a computer connected to the internet via a router. I configured the router in order to send the magic packet to this comp but it only works a few times (like 5 times and then it does not wake up my comp). Anyone had also this problem? Thank you.
 

audi2000

Distinguished
Mar 23, 2010
3
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18,510


I've been fighting with WOL configured to an Asus P6X58 MB with WRT160n router.
Never could get it to work with magic packet. So, as an alternative I did the following.
I first upgraded my router at the dd-wrt.com site whcih has built in WOL functionality.
I could activate locally but not via internet so I enabled remote support in the router.
Then had access to router via internet.
Gained access to router by setting up a proxy static ip via DNSexit. I then connect to router
and enable WOL on the PC via the router. No magic packet is involved. Very simple to use.
 
I hope you're at least using HTTPS, because it's a bit risky leaving your router accessible from the internet side, esp. w/ HTTP. HTTP means your username/password is passed in the clear.

In the case of dd-wrt, I’d encourage setting up a PPTP VPN server, or even better, OpenVPN/SSH server w/ private/public key pairs. All of these place you on the local network so you can generate the magic packet as a local user (I use the Linux ether-wake command specifically for this purpose). And because these are general purpose tools, you can use them for many other purposes (e.g., internet proxy).

As far as WOL only working a few times, that’s because the router is working off its ARP table/cache. But that’s flushed after about 10 mins once the device is turned off. And then WOL becomes inaccessible for that device. So it’s inherently unreliable.

The problem w/ sending the magic packet over the router’s WAN interface is that most routers (including dd-wrt) don’t allow access to the broadcast address of your network (x.x.x.255). But there are instructions available that work around this limitation.

http://www.dd-wrt.com/wiki/index.php/WOL

I currently use this method w/ both dd-wrt and tomato routers, works very well. Requires only clicking a link to wake any PC, which is particularly handy for mobile devices (e.g., iPhone).

There are many ways to deal w/ WOL, some better than others.
 

audi2000

Distinguished
Mar 23, 2010
3
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18,510
Good point regarding VPN. Router doesn't work with HTTPS though. Magic packet never worked local or internet for me even with the static ip. The magic packet is set up in my router to x.x.x.255 and my ip is also properly set.
I will use the routers VPN. Thanks!
 

2dumb2care

Honorable
Oct 14, 2012
11
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10,520

The problem is the arp cache of your router will refresh leaving your cold computer out of the list after 10 minutes to hours depending on the manufacturer, but they all do today. I reiterate pros/cons in this thread "Wake on LAN over the Internet"
http://www.tomshardware.com/forum/26000-41-wake-internet#t116289
by just using a cheap hub to broadcast the magic packet through-out my LAN. A switch won't work because they route the magic packet to only one intended device.

Trick is to set your router to port forward the magic packet to another device that is constantly on and is always in the arp list (a standby printer/fax is a good example, voip, range extender, etc.) but use the MAC address of the cold computer. With a hub that magic packet gets LAN broadcast to all connected devices, cold and hot. For a $10 - $15 used 4-port hub, its a cheap fix without a lot of hoops to jump or potential screwups of router firmware entries.