Gitlab pages - correct URL ? / nginx

I have started to try and sort out gitlab pages
I have created a domain pages.mydomain.com (different to my gitlab one, same server)
Added a wild card and the only line I have uncommented in the RB was
the gitlabpages external URL and edited it

I have checked the runner has built the files and made the public fodler. etc using my yml file which it has but if I go to settings > pages > its asking me to set up the yml file and not showing me the pages URL but when I try and visit I get an nginx 500 error anyway which is probably related to me running other stuff on the same server and not doing all kinds of docker stuff but

http://namespace.pages.mydomain.com/repo-name

I assume namespace is my group name the repo is in ?