Couldn't resolve host name

Hi everyone,

I've just installed GRAV as a docker container on my Ubuntu server.
I tried to install a new theme too, but during the installation process a warning message popped up:

I don't know what it is exactly about. Could the problem be due to the fact that my connection is behind CGNAT?
Thanks

The theme / online template does not exist .. its a 404 error.. so I think you might have a very old of theme, that has been abandoned.

https://codeload.github.com/getgrav/grav-theme-photographer/
Try outside your docker image , you will see.

GitHub - getgrav/grav-theme-photographer: Photographer Theme for Grav - Modern photography portfolio.

This is a link for the official photographer theme. Is this the theme you need.
It should be able to install via searching the theme section.