Thanks for the suggestion, it worked!
I followed this guide: https://docs.nodebb.org/en/latest/installing/os/ubuntu.html
I can access the forum using the ip address and port. I have pointed the IP address at the server.I have also changed the domain in config.json to my domain name.
When I visit the domain I get an error 521. I don't think that nginx was installed.
Do I need to install Nginx and then point the domain at the nodeBB folder?
You need to give more details about your configuration to get things done.
Pointing your domain to a server is just setting up an A record to an IP or domain alias. And yes, you need Apache or nginx webserver/proxy.
Sorry about the lack of detail. I think I realised what was wrong as I was typing and I've fixed it.
I had no web server :O.
@tomanagle can you get to the forum by using domain:port?