Due to a recent mishap with the web server that hosts this website, Ian wanted more flexibility hosting wise. He wanted the ability to host more than one web server. The problem of hosting more than one web server is you can port forward one port 80 and 443.
In a router, you can only point one port to an internal I.P. address. You could mess about trying to redirect web traffic on other ports, but that starts to get messy.
There is a solution to the problem. It is called a reverse proxy. This is something that directs traffic between the router and web servers.
A reverse proxy monitors the incoming web traffic, it reads which web address the data is for and directs it to the correct web server.
The solution Ian chose is tried and tested. It is called NGINX (pronounced Engine-X). NGINX will happily run on a Raspberry Pi, it also brings other benefits:-
Such as putting another layer between the router and any web servers. There are other benefits, a quick internet search will provide all the information if you have an interest.
On this occasion, Ian installed the NGINX software on an RPi 3B+, which seems to be capable of doing the routing perfectly.