Cloud flare ssl subdomain

Hello
we have an active lets encript ssl license on our domain as wildcard to it covers all subdomains
a.domain.com b.com
after moving dns to cloudflare ive enable cloudflare ssl as Flex, remove www record but only main domain and one subdomain, now only 2 domains, main domain and one subdomain are under ssl and other ones are out,
any suggestion ?

also ive enter cloudflare key into my server

If you have Let’s Encrypt on your site, you should use Full (Strict) ssl mode. Cloudflare will then cover the domain and all sub domains in the same way as long as they are all set to :orange:.

If you want Cloudflare to cover the root domain, you should enable Let’s Encrypt for that as well, or use www instead for that.