Remote HTTPS not working

Hi all,

so I get a little fed up with DuckDNS and the Google Assistance issue where it says Home Assistant isn’t available. I found this about setting up Dynu DNS: Add-on: Dynu DNS (alternative to DuckDNS) - Installation / Home Assistant OS - Home Assistant Community

So I moved everything from DuckDNS to Dynu. I haven’t tested the Google assistance integration because I’m now stuck with my DNS name not doing HTTPS. I basically followed this guide: Home Assistant Remote Access for FREE - DuckDNS + LetsEncrypt + Single URL

So, I installed HA, I have Dynu installed, I can access my HA from inside and outside my network without having to specify any ports. I then tried using Dnsmasq, NGINX and installing Lets encrypt (not sure if this is required) but Lets encryps is giving an error when I start

Certbot failed to authenticate some domains (authenticator: standalone). The Certificate Authority reported these problems:
Domain: XXXXXXXX.ddnsfree.com
Type: connection
Detail: xxx.xxx.xxx.xxx: Fetching http://xxxxxxxx.ddnsfree.com/.well-known/acme-challenge/7Od9teFi3NuMQSkcmA-Q3WpeCZgN_QRZzlq44bI: Error getting validation data
Hint: The Certificate Authority failed to download the challenge files from the temporary standalone webserver started by Certbot on port 80. Ensure that the listed domains point to this machine and that it can accept inbound connections from the internet.
Some challenges have failed.

Any help would be appreciated