Remotely turning on the computer (wake on lan) does not work after changing loca

Hello.

I wanted to be able to turn on my computer remotely from where I am currently on vacation. I configured UEFI, enabling the necessary options (MSI Z77A-G45 board), I wrote back the network card's mac from the console, in the router (connect box from UPC) I forwarded the port. I noticed that the router stops sending a signal to the card when the computer shuts down, so I added an exception in the router, giving it a mac, and from then on the computer started to wake up remotely. On the computer from which I want to wake up, I downloaded a small application "wake on lan", in which I enter:

- mac of the network card of the computer to be woken up
- external IP of the computer to be woken up (read from "my ip" websites, etc.)
- subnet mask: "255.255.255.255"
- the method of sending the "Internet" packet
- the port that I forwarded in the connect box

Before leaving, I tested it five times to make sure everything works by disconnecting from the connect box's wifi network and connecting to the one provided by the mobile (mobile hot spot, play network). I did longer time intervals between attempts. It worked every time. Currently, the only thing that has changed is that the laptop with the mobile from which I share the Internet is located in a different place in Poland. I control the state of the computer's operation through the team viewer. I send the magic package in the same way as on the spot, I share the link from the same phone.

What do you think could be wrong? Is there any chance to save this connection? The computer and the router are of course connected to the electricity on site.

Common Wake on LAN problems on home devices (computers). The entry in the ARP table on the router may have expired. There's no Intel vpro here so the computer won't renew the address lease, so gimme. The solution is to add a static entry to the ARP table in the router, the best solution is a router with openwrt and sending packets from its level.
DNS set up? After all, you have a floating address, and that's the basis of access from the outside.
PS: if the router restarted, it lost the ARP entry for 100% and the public address changed. The solutions to both problems are listed above. And to turn on the computer, all you can do is call someone and tell them to press the switch, and give them a public address. Then you must set Ddns on the router, and if the scrap from UPC allows, it is entered into the ARP table. And it's best to put Compal in bridge mode and its own router.

Unless a miracle happens and the computer turns on. Then only the activities described above without calling.

Wake on Lan is not a TCP/IP level application. This is a low level package. Port forwarding is not exactly what you think. At a low level, there is virtually no concept of a port.
It won't work if the router can't send it, you need to work here.

Load in:
https://en.wikipedia.org/wiki/Wake_on_LAN
https://en.wikipedia.org/wiki/Magic_Packet

By sending a Wake on LAN packet to a specific port, you can wake up the computer and port forwarding is definitely applicable here, because this packet must somehow get behind the NAT.

makosuu wrote:

By sending a Wake on LAN packet to a specific port, you can wake up the computer and port forwarding is definitely applicable here, because this packet must somehow get behind the NAT.

Then explain how, since in the LAN network it is a broadcast packet. A computer that is turned off does not have a TCP address, so NAT (TCP service) does not occur.

Yes, in this case the turned off computer has no address. But above I wrote about entries in the ARP table. And equipment with vPro normally renews the address, from there you can go to its website, force shutdown, turn on, restart, boot from USB.

makosuu wrote:

Yes, in this case the turned off computer has no address. But above I wrote about entries in the ARP table. And equipment with vPro normally renews the address, from there you can go to its website, force shutdown, enable, restart, boot from USB.

You're making too much guesswork. The ARP table is not necessary because it is broadcast etc etc ... the sleeping card itself detects what is addressed to it.

VPro is not Wake on lan (it is much older than the first one), although it is clear to human sense that their combination gives usable quality.
Don't connect this one phenomenon with what happens next.

In my experience, in this type of configurations, it only works when sending this packet from the router, because only then can it be a broadcast packet. It is not possible to send a broadcast packet addressed to the LAN over the Internet. The router will pass the unicast MagicPacket through the redirected port and direct it to the interface associated with the destination IP address (usually redirects), but as already noted, only until it has the IP address of this computer in its ARP table. In addition, a switch and its switching table are integrated into the router along the way. There, after some time, the MAC address of the turned off computer will expire.

I read before setting up just about ARP. The idea was to add the card's mac address as an exception to be turned on by the magic package. I don't know if I found the right tab in the router options, because sometimes they are under different more friendly names (with ARP in the name I didn't come across after looking through all the tabs), but I found something that looked familiar There was a list of devices that are connected to the router, mac addresses, and expiration times in milliseconds (?). At the very bottom there was an option where you could add a mac address and mark it as an exception to these rules and not apply to it at this time. That's what I did, because earlier the computer was able to be turned on remotely once, and after some time not anymore. After adding this rule, this problem disappeared and I specifically waited a few hours to try again to see if it would expire and it was successful.

In UPC, i.e. where the computer to wake up is located, I have a fixed external IP. I definitely have a dynamic IP in play from which I am trying to connect to that computer, if it matters.

Port forwarding from what I read is required, when we send a packet from a network other than local, the unknown port may be blocked.

Włodi wrote:

There was a list of devices that are connected to the router, mac addresses, and times in milliseconds after which they expire (?).

Not in ms, just in s... and that was the DHCP table. A static IP address reservation is not the same as a static ARP entry. The router sends the packet over the Ethernet interface, so it must wrap it with an Ethernet frame. To do this, it needs to know the destination MAC address, which corresponds to the target's IP address. For this purpose, it uses ARP - if communication with this host has already taken place, there is an appropriate entry in the ARP table, if not (or it has been inactive for a long time), then there is no entry. Thus, before sending the proper packet, an ARP request is broadcast for the MAC address of the host with the indicated IP address. Unfortunately, the computer is turned off and will not respond to such a query. Due to the lack of response, the router does not know how to address the Ethernet frame containing the Magic Packet. Does your router have the ability to remotely log in to its configuration panel (under the external IP and on the indicated port)? If so, is it possible to initiate WOL from the configuration panel? In DD-WRT it looks like this:


After thinking about the matter, the only problem may be the ARP of the router, because the MAC table of the switch will also expire, but here it will manifest itself in sending the frame through all interfaces.

Włodi wrote:

In UPC, i.e. where the computer to wake up is located, I have a fixed external IP. I definitely have a dynamic IP in play from which I am trying to connect to that computer, if it matters.

In Play, you don't even have a public IP at home, and it doesn't matter.



Compal 99% has no option to add a static ARP entry or send WOL packets. It's best to switch it to bridge mode and connect your own router.

WoL packets can be sent over the internet and I checked that. This is 100% working. I even use it often.

Włodi wrote:

In UPC, i.e. where the computer to wake up is located, I have a fixed external IP.

On what equipment does UPC work there - modem and its own router or modemorouter, is there no IPv6 enabled there?

The modem router and the computer is connected directly to it with a cable. This is a Compal router, as someone wrote above. I have now found a model on the forum that may be Compal CH7465LG-LC. In UPC it is called "Connect Box". The look is right. At the input there is a coax with a signal from them, at the output there are four ethernet ports and two telephone ports. It is possible that IPv6 is enabled. In the console after typing "ipconfig /all", if I remember correctly, there was also some address in this line. Modem settings are default, the ones I modified are described above. I found the user manual, which I put in the attachment, you can see the individual settings screens there.

Włodi wrote:

It is possible that IPv6 is enabled. In the console after typing "ipconfig /all", if I remember correctly, there was also some address in this line.

Call UPC what they would turn off if IPv6 is unnecessary.

As such, the external IP is only there on the modem router and not on the specific client end device:
- it is not possible to use WOL from the outside (from the Internet) - no possibility to redirect traffic from the WAN to the Broadcast address of the LAN
- no access from the outside (from the Internet) to the router configuration page - although there is an option to enable it - a parental lock message pops up.

Compal's bridge mode (but only IPv4) and your own router with WOL support may help here.