I am trying to setup my own gitlab server on a headless server running ubuntu. I installed gitlab using the command line. I changed the external_url in the gitlab.rb file to the ip address of the server on my network.
When I try to navigate to the ip address of my server in the web browser of another computer I cannot see the dashboard. How can I access the dashboard from another computer?
As mentioned in Configuring the external URL for GitLab, make sure to run sudo gitlab-ctl reconfigure for the change to take effect.
That applies to the Omnibus installation, which is best done using a GitLab docker image.
If the service answer locally (as per comments/discussion), then it is a network or firewall issue.
As how in "How To Install and Configure GitLab on Ubuntu 16.04", you might need to adjust firewall rules:
sudo ufw allow http
sudo ufw allow https
sudo ufw allow OpenSSH