cert

Hi, I am new to CloudFlare and web deployment. I did purchse a domain and hosted a static website in cloudflare form github. in some of the computer/network it working fine.. it's opening and in some network and location it's not opening and browser is showing error as attached in screenshot. Can any one help me please with the steps I need to follow to configure SSL/DNS if I am doing something wrong somewhere. Please let me know if you need any futher information to diagnose and fix this issue.