In my case, it is set up in this way. Have a try...
You said you are able to get it work internally. Just skip 1.
1. Startup the WoL on your computer.
Step 1 Go to BIOS,in Power Management Setup,please enable Wake Up On LAN or Resume by LAN.
Setp 2 Make sure your network adapter support Wake on LAN.Then go to Device Manager,open the adapter’s properties->advanced,please find Wake up Capabilities and set the value to be“Magic Packet” or ”Both”
Note:In different computers and adapters,the option’s names may be different.Please refer above to startup the WoL on your computer. If you can’t find the the relative options,that means your computer or adapter do not support Wake on LAN.

2. We need to set port forwarding for the magic packets in the modem.
Step 1 Log into web-based utlity, 192.168.1.1.
Step 2 Click on Interface Setup->LAN,change the subnet Mask to be 255.255.255.128
Step 3 Go to Advanced Setup---NAT---Virtual Server
Step 4 Add a rule and fill in the content.



Step 5 Save the settings and now you can wake up the computer from the internet with WAN IP of the modem and the port.Here is a tool named Depicus for testing,
download link http://www.depicus.com/wake-on-lan/wake-on-lan-gui.aspx.You can also use other tools.

Thank you Ada. It works fine for me.

TD-W8961NB V1

TD-W8961ND - HW Version 3 - Firmware 3.0.0 Build 120720 Rel.09287
Italy

For me it did not work.
My PC setup is OK (WOL works from within LAN); it used to work from WAN before replacing my old modem/router with the model mentioned above.
In both cases:
I have setup IP subnet mask as 255.255.255.128
The rule I added was: Any application/ ALL protocols / port 9 / Local IP 192.168.1.127 (in my opinion port number matters, shall be that used in sending the magic packet)
I have defined no routing rules and tried also with firewall disabled. No success.
I do my (tested) testing by means of my smartphone: I disable LAN on it and access Internet via the mobile operator (I use a DDNS service). It used to work but not with the new modem/router.
I have tried (in both cases) also to access my Apache server (on same computer, same testing mode, adding the NAT rule for port 80) with identical results: It used to work, but not with the new modem/router.
Suggestions?

I solved my WOL problem
it works, but only if I've add the specific MAC-IP Binding to the ARP List.

1- Subnetmask 255.255.255.0
2- Forwarding / Virtual server/ ip: 192.168.1.100 (Wake device ip)
3 -DHCP Address Reservation: 192.168.1.100 (Wake device ip)
4- IP-MAC Binding: 192.168.1.100 (Wake device ip)

Model No. TD-W8970
Firmware Version:0.6.0 1.2 v000c.0 Build 130201 Rel.54921n

ginsi wrote

TD-W8961ND - HW Version 3 - Firmware 3.0.0 Build 120720 Rel.09287
Italy

For me it did not work.
My PC setup is OK (WOL works from within LAN); it used to work from WAN before replacing my old modem/router with the model mentioned above.
In both cases:
I have setup IP subnet mask as 255.255.255.128
The rule I added was: Any application/ ALL protocols / port 9 / Local IP 192.168.1.127 (in my opinion port number matters, shall be that used in sending the magic packet)
I have defined no routing rules and tried also with firewall disabled. No success.
I do my (tested) testing by means of my smartphone: I disable LAN on it and access Internet via the mobile operator (I use a DDNS service). It used to work but not with the new modem/router.
I have tried (in both cases) also to access my Apache server (on same computer, same testing mode, adding the NAT rule for port 80) with identical results: It used to work, but not with the new modem/router.
Suggestions?

ilkertr said:

I solved my WOL problem
it works, but only if I've add the specific MAC-IP Binding to the ARP List.

I eventually found that my problem was on DDNS, not in port forwarding as I had (erroneously) supposed.

As for the specific problem of WoL, in my opinion:

- The ARP solution is *not* a real solution, because ARP lists are often (and should be, to allow automatic subnet reconfiguration) volatile, i.e. subject to automatic change in time. Therefore you will also probably find that such a solution works for a certain time, but ceases to function after some time elapses (unless you can - I don't know - to make the relevant entry in ARP table permanent): this solution is based on a scheme like this: (1) from "outside" Internet a packet requiring a certain port (9, in most cases) comes in; (2) your router (NAT/Virtual server) sees that packets for that port shall be rerouted to a subnet address (192.168.1.100 in your case); it (hopefully) sees from ARP tables that the subnet address shall be directed to the corresponding MAC address.

- The good solution should be similar for what concern point (1) but: (2) your router (NAT/Virtual server) sees that packets for that port shall be rerouted to a subnet address *which correspond to a broadcast address*, so that is pointless to look in ARP tables; It must be broadcasted to all MAC addresses, using the LAN-level broadcasting. (3) the packet reaches all the computers in the subnet, but has meaning only for computers willing to accept it (this happens basically in hardware, recognizing multiple occurrences of the MAC address contained in the magic packet).

In short: you should rely on IP level broacasting; I obtained this by defining my subnet address as 255.255.255.128, which - since my subnet starts with 192.168.1... - causes address 192.168.1.127 to be recognized as an IP broadcast address.

Try this and please let me know.

I tested two ip config yersterday but i received below same error message:

subnet Mask to be 255.255.255.128 and Virtual server ip 192.168.1.127
subnet Mask to be 255.255.255.0 and Virtual server ip 192.168.1.255

error message:

"Error code: 4937
The IP address is not in the same subnet with LAN IP address. Please input another one."

I solved my WOL problem today
I solved the only way to

1- Subnetmask 255.255.255.0
2- Forwarding / Virtual server/ ip: 192.168.1.100 (Wake device ip)
3 -DHCP Address Reservation: 192.168.1.100 (Wake device ip)
4- IP-MAC Binding: 192.168.1.100 (Wake device ip)

Well, your solution is probably neat since your modem/router supports IP-MAC binding (this had slipped my eyes, I had assumed you were patching ARP tables via telnet..).

In my case I have a simpler modem/router and IP-MAC binding is not supported. I had also problems with the 255.255.255.0/192.168.1.255 solution (don't know the reason), but they disappeared when I changed to 255.255.255.128/192.168.1.127.

I am not sure where the problems come from and I am pretty curious about this. In case you want to experiment a little more: I have seen (from the setup pages that you posted) that your DHCP covers addresses till 192.168.1.199. This seems to me in contrast with the ...128 subnet mask; may be your "Error code 4937" comes from this or similar incompatibility?

I also wonder what the router will do in case it knows that the IP mentioned in the binding is not active (DHCP "leased time" expired?); not sure if this has really sense, but if it does, the router might perhaps discard the packet...)