[Plugin: Constant Contact for WordPress] Page Cannot Be Displayed – Error On Submit

Hello,

I’m working on a site that’s still just in IP mode: https://204.42.144.129/join-mailing-list/

When I test the form, I get an error:

The page cannot be displayed

The page you are looking for cannot be displayed because an invalid method (HTTP verb) was used to attempt access.

Any suggestions?

Thanks,
~Robin

https://www.ads-software.com/extend/plugins/constant-contact-api/