"Could not reach Comfortclick. Please try again." message google smart home

Hi

I'm trying to integrate Google Home with Comfortclick, but when I go to add a device in Google Home, I get the following message: "Could not reach Comfortclick. Please try again.". I have followed all the steps of the video, I have even declared the public IP on your website, but nothing. I am using a DDNS server. How can I solve that?

Thanks.