To setup an actual demo of this for my team, I've installed the system, figured out everything that the documentation is missing (which is a lot) and finally having a working demo, but it's configured to redirect everything back to 'localhost' by default - this is annoying to say the least. 

Is there a configuration file somewhere in here that I can change this so that I can have my team simply go to the IP of the server that is hosting OP and have them demo it?

I have the same issue.

I've installed on my domain and it works. But when I navigate to adiminstration/account pages it redirects me to 127.0.0.1.

I've tried to change URL on Settings > General, but it has no effect.

Can someone help me, please?

Thanks in advance.

I've only ever installed OP on a cloud based webserver so I'm not sure if I am going to be much help here as you both want to set it up on a local network... However I will try...

Have you checked that apache is configured correctly?

Have you tried specifying your IP in the openproject.conf virtualhost found in /etc/apache2/sites-available/?

Include /etc/openproject/addons/apache2/includes/server/*.conf

<VirtualHost *:80>
  ServerName <OP Server FQDN>
  DocumentRoot /opt/openproject/public

  ProxyRequests off

  Include /etc/openproject/addons/apache2/includes/vhost/*.conf

  # Can't use Location block since it would overshadow all the other proxypass directives on CentOS
  ProxyPass / http://127.0.0.1:6000/ retry=0
  ProxyPassReverse / http://127.0.0.1:6000/
</VirtualHost>

so change <VirtualHost *:80> to <VirtualHost x.x.x.x:80>

Have you tried changing the port if there is potentially a conflict with the 000-default.conf site or another site on the same port?

I have the same issue.

Can someone help me, please?