Symptom
After you configure a certificate, the website displays normally in Chrome. However, Firefox warns that the website is insecure.
Possible cause
Your server uses weak encryption algorithms.
Solution
You can configure your website to use the recommended cipher suite ssl_ciphers ECDHE-RSA-AES128-GCM-SHA256:ECDHE:ECDH:AES:HIGH:!NULL:!aNULL:!MD5:!ADH:!RC4 and protocols ssl_protocols TLSv1.1 TLSv1.2 TLSv1.3.