Switch from DuckDNS to Personal Domain - Let's Encrypt issues

 had been using duckdns for my domain to connect to my HA since I installed it. However, I recently bought myself a domain name to use for my personal sites and for HA, as I found duckdns becoming less and less reliable. I am unable to configure HA to use Let's Encrypt.

I have tried to configure it from the instructions I found

email: RECACTED
domains: 
- REDACTED
challenge: http
certfile: fullchain.pem
keyfile: privkey.pem

but I keep getting this kind of error:

It's the same error if I use "challenge: dns"

I have uninstalled duckdns, uninstalled and reinstalled Let's Encrypt. I just can't get it to work. If it is any help I registered my domain with WHC (Web Hosting Canada). I know the WHC side is setup correctly as I was able to use Let's Encrypt to get a cert for my hobby sites and they are working as expected.

When I was using duckdns, I was forwarding port 8443 to 8443; but after some research into my error, I tried at least to get the cert by forwarding port 80 to port 8123 and saving the config; but still no luck.

My config:

• Home Assistant OS
• Core: 2025.9.1
• Supervisor: 2025.08.3
• Operating System: 16.1
• Frontend: 20250903.3

Thx