Use docker registry in omnibus gitlab docker container

Is is it possible to use the docker registry in the omnibus gitlab docker container?
I try it for days and go from error to error and doesn’t find a solution.

The standard configuration:

I use nginx as a proxy for the container to port 80 in the container, but the abc.com:5000 throws errors like:

400 Bad Request
The plain HTTP request was sent to HTTPS port

If I deactivate the registry nginx listen_https it throws certificate errors.

Is there a way to configure the nginx inside and outside correct to use the registry or is it a better way to deploy a real external registry?