I added a Opt-in into the footer of my Helix Ultimate Website, put the API and the list ID into the settings and have an error when submiting the form.

cURL error: Could not resolve host: .api.mailchimp.com

I've logged into the server and successfully pinged api.mailchimp.com

PHP is compiled with Curl and it's activated and available.

I ran a curl test and was able to connect:

[root@hosting ~]# curl --request GET \
> --url 'us18.api.mailchimp.com/3.0/' \
> --user 'MYUSER:86d6adfexxxxxxxxxxxx337bcee902-us18'

What it seems to me is that the request is not adding the datacenter to the URL reqeust.

In this case it's: us18

Also, I'm also assuming that the API key needs to be in the format as <userID>:<API>

Is this a design flaw in SP Page Builder that needs to be updated to work with Mailchimp?