@클라이브_A 

Hello.

I tried your suggestion, but the result is the same as the questioner.

But I think some of your suggestions are correct.
Because, as you suggested, if you connect to the port of the NVR through DDNS,
The same situation occurs as the problem situation.

However, by connecting DDNS with IP of CCTV rather than NVR, the network automatically sets HTTPS and STREAM for port forwarding and confirmed that the screen is output normally when connected with IPC.

And in the IPC of CCTV, there is an item that automatically or manually sets port forwarding on the network, but there is no setting for port forwarding on the network of the NVR.

Therefore, there is a continuous problem of failure to load CCTV screens connected to the NVR through DDNS through port forwarding of the NVR.

Is the above issue a situation where I need to get a separate certification of HTTPS?

It works fine with VMS, but why does the WEB UI on the NVR only show the NVR GUI and the CCTV channel keep failing to load?

I am wondering to you whether this issue is a structural difference due to the wrong code for your company's service or a matter of simple certification.

Thank you.

  @David_Jung 

I just solved this problem.

I activated UPnP in the network from external DDNS in the NVR and manually changed the MAPPING TYPE.

And I changed the external port of HTTPS in NVR from router.

And I entered it like this in the address window.
>> DDNS: External Port(UPnP의 External Port)

I hope it helps users who suffer from this problem.

This was not a matter of authentication of HTTPS!!!