GitLab opens on eny subdomain

Hello everyone.
After few days trying to get GitLab work on my Gentoo server, I gave up and installed Debian with GitLab omnibus package.
It’s quite different and I can’t understand some things.
GitLab think I need it EVERYWHERE and it’s nginx serves for any subdomain.
Despite “external_url ‘’” in /etc/gitlab/gitlab.rb, I have GitLab on,, etc.
What’s his problem and what is the cure for such enthusiastic omnibus-GitLab?