DuckDNS Proxmox not working

Configuration
1

I have a fresh install of HomeAssistant on Proxmox. My first add-on is DuckDNS. I cannot get this to work though (that is, I can neither get local https logins nor access the new duckdns-issued domain from my phone, using phone internet, not wifi) . I imagine there must be some Proxmox settings that must be added but so far have not been able to find them by searching the web. Can anyone help get me unstuck here? (over 8 hours on this already…)

(my goals for the https access are 1) remote access from phones and 2) https setup for espHome to allow writing firmware to ESP32)

No issues creating the domain at DuckDNS. Got the token and the startup of DuckDNS on HomeAssistant went fine…

DuckDNS log: (domain name changed for privacy)

[09:21:59] INFO: Starting DuckDNS...
[09:22:00] INFO: Renew certificate for domains: fincajill.duckdns.org and aliases: 
# INFO: Using main config file /data/workdir/config
Processing finxxxxxxx.duckdns.org
 + Signing domains...
 + Generating private key...
 + Generating signing request...
 + Requesting new certificate order from CA...
 + Received 1 authorizations URLs from the CA
 + Handling authorization for finxxxxxxx.duckdns.org
 + 1 pending challenge(s)
 + Deploying challenge tokens...
OK + Responding to challenge for fincajill.duckdns.org authorization...
 + Challenge is valid!
 + Cleaning challenge tokens...
OK + Requesting certificate...
Warning: Will read cert request from stdin since no -in option is given
 + Checking certificate...
 + Done!
 + Creating fullchain.pem...
 + Done!

DuckDNS config file: (domain name and token changed for privacy)

domains:
  - finxxxxxxx.duckdns. org  #space inserted to allow for posting here
token: 77e9xxx3-4xx9-xxxx-xxxx-xxxxxxxxxxx
aliases: []
lets_encrypt:
  accept_terms: true
  algo: secp384r1
  certfile: fullchain.pem
  keyfile: privkey.pem
seconds: 300

On local network when I go to https://(the ip address):8123, chrome indicates that https is not active.

Trying to connect to finxxxxxxx.duckdns.org from my phone, wifi off, it never connects and just times out.

I worked from this tutorial: Home Assistant Remote Access using DuckDNS and LetsEncrypt - Smart Home Addict

What am I missing here?

Thank you!

2

First if you are using the NGinX, then your local access to port 8123 will not be HTTPS, but HTTP.
NGinX will have another port that is handling the HTTPS and then forward any data on that to the local port 8123 over HTTP.

For HTTPS to work you need to have set up a portforward in your router to the the HTTPS port on NGinX, like 443 maybe.
For a portforward to work you need a public available IP address. It does not have to be static though.
If your public IP address on the router starts with 100, then you are probably behind a CGNAT and you either need to contact your ISP to get a public available IP forwarded to your router or you need to look into some tunnel, like a cloudflared setup.