Setting up NGINX reverse proxy for DO function

I am trying to setup a reverse proxy for a DO function so I can use our standard domain on the function. I have setup a new droplet and setup NGINX to do this.

I have configured NGINX as such:

server_name api.mydomain.com;
location / {
proxy_pass https://mydofunctionurl/test;
include proxy_params;
}

I am having Cloudflare errors being returned. I assume Cloudflare is on the DO Function as I have not configured Cloudflare on the droplet.

Error:

## DNS resolution error
## What happened?
You've requested a page on a website (api.mydomain.com) that is on the [Cloudflare](https://www.cloudflare.com/5xx-error-landing/) network. Cloudflare is currently unable to resolve your requested domain (api.mydomain.com). There are two potential causes of this:

-   **Most likely:** if the owner just signed up for Cloudflare it can take a few minutes for the website's information to be distributed to our global network.
-   **Less likely:** something is wrong with this site's configuration. Usually this happens when accounts have been signed up with a partner organization (e.g., a hosting provider) and the provider's DNS fails.

Any ideas on how I can correct this configuration?