WEB IDE not able to load project data

Summary

I'm running a GitLab self Hosted Instance with Apache instead of NGINX configured with the help of https://medium.com/@joscelyn56/install-and-configure-gitlab-on-your-vps-edb5e522b866

Everything is working fine but the Web IDE is not able to load.

Steps to reproduce

Follow the Guide linked above, as well as the HTTPS Enable Guide that is linked in that guide. Create a new Project (in my case based on a template) and try to open Web IDE.

Example Project

Not provideable on Gitlab.com

What is the current bug behavior?

WEB IDE Fails to Load the Project under /api/v4/projects/root%2Fspringtesttemplate

What is the expected correct behavior?

WEB IDE Loads and makes it possible to edit files.