Letsencyrpt setup fails for host with internal IP address

Hi, I am attempting to set up discourse on an ubuntu machine for first time. The intent is that the platform will only be accessible from within our company network, hence the IP address for the hostname registered with our DNS provider is an internal IP.

I am using instructions from https://www.howtoforge.com/tutorial/how-to-install-and-configure-discourse-forum-with-nginx-on-ubuntu-1604/

I have successfully bootstrapped and launched. However step 3 is failing (Generate SSL Letsencrypt) with following error:

Failed authorization procedure. (http-01): urn:ietf:params:acme:error:dns :: No valid IP addresses found for

nslookup on the machine can find the IP address from the hostname, and I can also ping the hostname

I think it has something to do with the fact the the IP address for the host is an internal address. I found this article but I’m not sure how to proceed. No valid IP addresses found for (my domain) - Help - Let's Encrypt Community Support

Let’s Encrypt needs to access the your IP address from the Internet.

The following topics/posts may help you: