hostname vs FQDN

Hi,

We are running gitlab-ee 12.3.5 on Ubuntu 16.04. When accessing projects we get 404 errors when trying to access pages using the short hostname of our server e.g. http://gitlabsrv/projectname. If we use the FQDN (http://gitlabsrv.example.com/projectname) the projects are accessible. Both gitlabsrv.example.com and gitlabsrv are in the hosts file so it there a way to ensure that the short URL points to the same place as the FQDN URL?