Hi, hope their is someone here that is able to point me in the right direction. I have been working on this for a few weeks without any luck in resolving it.
Firstly the environment:
Nextcloud is running on its on proxmox VM running ubuntu-20.04.1-live-server-amd64
Nginx is running also on its own proxmox VM running ubuntu-20.04.1-live-server-amd64
Installed Collabora on its own proxmox VM, also running ubuntu-20.04.1-live-server-amd64
using the following tutorial as a guide: link
Please note: that this tutorial differs from my environment as it installs Nextcloud, Collabora and NginX on the same VM.
The issue:
As I use different VMs, I first tried to configure Nginx by adding a new conf file called office.domain.com.conf and adding the values mentioned in the tutorial to it. This did not work for me as Word documents would not open and would only display a white page.
Then, I decided to removed the specific collabora code from the Nginx office.domain.com.conf and created the reverse proxy using appache2 on the collabora VM itself as described in the tutorial. This got me a step closer to resolve, as collabora would load more than the white page before.
As you can see in the below screenshots, it will load collabora mostly but than stops:
I cant figure out what is going wrong.
Hope someone can help me get it to work. 
Thanks so much.