NCP: Port Forwarding not possible| open but closed | ZyXEL VMG1312-B10A

I use the latest NCP image from ownyourbits.

I’m getting absolutely insane as I simply cannot open the ports and access from the Internet.

  • Local access works well, no issue.

  • I use a ZyXEL VMG1312-B10A Router.

If I open Ports manually, I cannot reach the NCP from the Internet:

Bildschirmfoto vom 2020-12-29 15-18-35
(I’m aware that on the screenshot it’s deactivated.)

and the ports are shown as closed:

Bildschirmfoto vom 2020-12-29 14-14-12

If I enable UPnP in the router and use NCP to open the ports, I succeed and can reach the NCP from the Internet.

Bildschirmfoto vom 2020-12-29 15-18-47

Bildschirmfoto vom 2020-12-29 15-19-23

But I should “disable” UPnP as it poses a security risk.

If I do that, the ports are closed again, and I cannot access the NCP from the Internet.

What is going on?

My guess is that this is simply a useless router and I’d better buy a Fritz!box…

Any suggestions before I order one?

As this is perhaps more of a router related question, I have raised the issue on the ZyXEL forum as well. And got this answer.

Have you considered using the DMZ settings of the router?

The user guide available at ftp://ftp.zyxel.com/VMG1312-B10A/user_guide/ talks about them because that is often a way of allowing access to certain services on LAN from the Internet.

I did not know anything about DMZ and so had a brief read on what it is. Is anyone having experience with enabling DMZ to allow server access? Is this considered safe?

Just to close this off.

I eventually bought a Fritz!box - fed up with that stupid ZyXel thing.


As a last option, I could have tried is to reset the router. This might have worked. But that only came to my mind after I ordered.