DNS not working @sub-domain

My site is working fine with Cloudflare whereas, the sub-domains show the server not found error.

Ex : example.com - This works fine
Sub : subdomain.example.com - This doesnt

I have also tried updating the CNAME but doesnt works if any steps with link share.

Is the main site using a CNAME? It sounds like a DNS issue. What’s the domain?

At least the main domain looks fine. Which CNAME were you updating? And what’s the subdomain?