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I'm having an issue using Wake-on-LAN from the WAN, after everything has been configured correctly.

First of all, no problems waking up the PC from inside the LAN. Always works.

When it comes to WAN, it also works for me at first. But after a certain amount of time, let's say after 5 minutes have passed, it stops working, no matter how many WOL packets I try to send.

Any ideas?

BTW, I'm using a wired interface (ethernet).

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This is usually caused by your router not having a static ARP mapping (IP address to MAC address mapping) for your sleeping client. Dynamic ARP mappings usually time out and get deleted after a few minutes of disuse. So when your router gets a Wake-on-LAN packet to forward to the sleeping client a few minutes later, it doesn't know what MAC address to send it to. It doesn't matter that 16 copies of the target MAC address are contained inside the payload of the packet; most routers don't contain any code to recognize the format of a Wake-on-LAN packet and use the MAC address from the payload as the destination MAC address for the Ethernet header it needs to create.

Configure your router to have a static ARP mapping for that client. If you don't have a way to do that in your router, consider upgrading to aftermarket firmware like OpenWrt, DD-WRT, Tomato, etc., or upgrade your router hardware to something more flexible/advanced/geek-friendly.

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  • Hi friend, If you meant to static DHCP leases, then it's already configured - I mean that I matched the relevant PC IP to it's MAC adress... So the router/switch wont change the IP address for the designated PC.
    – Ami
    Nov 17, 2015 at 21:19
  • @Ami Nope, I said what I meant. Static DHCP address leases are a completely separate thing from static ARP mappings, even though both may involve an IP address and a MAC address. Most routers that offer static DHCP lease entries are not smart enough to also enter static ARP mappings for the same client.
    – Spiff
    Nov 17, 2015 at 21:23
  • I learned something new today. is there any alternative from defining an ARP mapping? as I understand DHCP lease is less 'strong' for the mentioned use.
    – Ami
    Nov 17, 2015 at 21:43
  • There's no alternative as universally applicable as defining an ARP mapping. Apple products have sophisticated Ethernet and Wi-Fi NICs that keep a tiny low-power microcontroller awake in the NIC even when the host is asleep, and this microcontroller keeps ARP, DHCP, and Bonjour service advertisements alive. Server-class Ethernet NICs often have a "Lights-Out Management" or "Out of Band Management" feature that does something similar. But "buy new hardware that supports a more sophisticated set of sleep/WoL features" is probably not the answer you were looking for.
    – Spiff
    Nov 17, 2015 at 21:58
  • is there a home/office router/switch you can recommend? (Supporting ARP config)
    – Ami
    Nov 18, 2015 at 17:32
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Ok, so after a recent research I have done, I came to 2 solutions for the problem:

The First one would be to set up an ARP cache as also Spiff suggested. So one of 'the best of 2015' routers that do support this feature would be the Archer C7 from TP-LINK. in router's manual you would be able to locate the regarded information by searching for "ARP List".

Second Solution is less home-user-friendly, however it's still a good solution for whoever finds out it possible. You can set up a PC/Server running a server OS, and configure it as a DHCP server. One of options there would be the STATIC ARP CACHE.

Hope I helped somehow with my two cents./// Peace and love.

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