Important before you do this:
- Make sure no CAA DNS record is preventing a request.
- Make sure the correct DNS for all relevant root or subdomains are pointing to the right proxyserver.
Visit the "External request" plugin from your hosting panel ans logged-in enduser. Not reseller level, you need enduser level.
enter domain WITH www if it should cover www.fulldomain.com AND fulldomain.com
OR
enter domain with subdomain if it should only cover thesubdomain.domain.com


Follow instructions, this can take a minute if the 2 pre-conditions are met.