How to access an L2TP server VPN behind router the ASUS n16?

In local network there is a computer on which you configured the L2TP VPN (Mac OS Server). It is connected to the asus router n16. How can I access it from the outside? As I understand it you need to forward some ports on the router to this computer, but what?

1723 tcp/udp, 1701 udp is not enough
September 26th 19 at 06:34
2 answers
September 26th 19 at 06:36
According to IANA (and I'm inclined to believe them), for the Protocol to work you need ports 1701 for the protocols udp and tcp
Ports 1723 and used for another.
As it turned out still need ports 500 and 4500 - Darius_Ko commented on September 26th 19 at 06:39
Ah, well, if you are using IPSec+l2tp Yes. In the sense that different implementations of VPN. (why do you need port 4500 - I don't know it's your custom) - Daryl23 commented on September 26th 19 at 06:42
udp 4500 NAT-T - tamia_Abshire commented on September 26th 19 at 06:45
and really. Do not know =) - Daryl23 commented on September 26th 19 at 06:48
September 26th 19 at 06:38
L2TP over IPSec
L2TP traffic – UDP 1701
Internet Key Exchange (IKE) – UDP 500
IPSec Network Address Translation (NAT-T) – UDP 4500
Allows IPsec Encapsulating Security Payload (ESP) traffic to the VPN server is UDP 50

In General you can read here:

Do not forget that even if the server is still behind a NAT to behind a NAT, you must connect to the registry to register the key.

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