Multiple private docker repositories on a host

Hi all,

I have been granted access to a remote host which already has docker repository installed and it’s on port 5000. Now I would like to create a new repository, get it tested and if everything goes fine, I will delete the old repository image. So for now since my users are using that old docker repo, I can remove it therefore I will have to get the new registry running on a different port, i.e. 4000. I tried by running the following the steps at the end of this page:
But it doesn’t looks like that it worked properly, I’m sure I made some mistakes here, can someone please help me figure this out?

docker run -d -p 4000:5000 registry:2

docker pull ubuntu

docker tag ubuntu localhost:4000/myfirstimage

docker push localhost:4000/myfirstimage

But when run curl: curl
I get this error: 404 page not found

Please help!

Thanks in advance