Tls: handshake failure adding domain's Let's Encrypt certificate on my VPS server

I was getting this error after creating a new subdomain: Domain could not be validated, error message: error type: urn:ietf:params:acme:error:tls, error detail: 2606:4700:3033::ac43:9854: Fetching remote error: tls: handshake failure

I tried this: Troubleshooting Cloudflare Universal SSL | Hostinger Help Center
I also purged the cache.

I see most people just install an origin certificate to bypass this issue: Origin CA certificates ยท Cloudflare SSL/TLS docs

I see this helped someone else but not sure how to do this: