Issues redirecting external visitors to localhost on pi

Hi, I’m pretty new to this so please forgive the ignorance. I’m not a coder expert but just trying to pick things up a bit more.

So, I have followed this guide to install wordpress: https://www.raspberrypi.org/learning/web-server-wordpress/worksheet.md

This happens successfully and I can run it from the localhost. However, as I try to access it externally, it does not allow any visitors. Here’s a summary of what I have done:

Running apache to listen and serve to *:8888.
Port 8888 is open and set to port forward to my pi, which is connected by LAN (static internal IP of 192.168.0.20)

I did a test install and managed to get it to work by luck by replacing the site url and wordpress address with my <external ip>:8888, however when my ip address resets, it caused the whole site to go down.

Now, I’m trying to see what to do with 1) getting a fresh install and everything to access externally again 2) a DNS that supports a specific port. I’m using dreads.afraid.org but they do not let me input a specific port, and I don’t know how to configure a DNS client to go to a specific port. Is this something other DNSes allow, but requires paying a fee?

Any help will be greatly appreciated as I have spent many hours trying to fix this!

Thanks