git clone works only for Public repositiory

Hello,

I have a GitLab installation on CentOS 7 server. The GitLab version: 11.9.8-ee

The "git clone" command works well for Public projects, but not works for Internal and Private projects. I got this below error message:

$ git clone git@mydomain.net:Ferenc/upload_test4.git
Cloning into 'upload_test4'...
GitLab: The project you were looking for could not be found.
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

Is it works as designed or is there a misconfiguration?

Thank you!