Quick correction, Cloudflare is not a hosting provider and could only possibly be considered when using Cloudflare Pages, which does not seem to be the case.
Regarding your error, the reason you get that the site can’t be reached for www.planningmywedding.renaymeshellevents.com is that you don’t have a record for the www.planningmywedding subdomain, you would need to add it.
As for your initial question, if the SSL/TLS mode for your zone is set to Full, you’ll need to make sure that the server has a valid origin certificate, for example.
You can refer to our documentation for the most common causes on the link below: