Facebook can't validate Let's Encrypt SSL Certificate, why?

[KangJL]

Most likely you need to do this

A Full Guide To Cloudflare

Hello, I will show you how to easily set up Cloudflare, Edit Records, and Troubleshoot with images! PLEASE READ BEFORE STARTING!!! Cloudflare cannot be used on free subdomains from InfinityFree. You can use Cloudflare on Custom Domains (yoursite.com) and with Custom Sub-Domains (subdomain.yoursite.com). A video tutorial can be found at the end of this guide, should you get stuck. You must connect your domain to your InfinityFree account first. Read more here. Set-Up Cloudflare Go to Dash…

I assume this is your custom subdomain.