Redirecting to https://
Once the certificate is issued, make the site always open over https://:
- In DirectAdmin: Account Manager → Domains → your domain → turn on Force SSL with https redirect.
- In WordPress: under Settings → General both addresses (WordPress and Site) must start with https://.
The padlock is crossed out or missing ("mixed content")
The page loads over https:// but pulls some images, scripts or fonts over http://. Change http:// addresses to https:// in the site's content and settings. In WordPress the Better Search Replace or Really Simple SSL plugins help.
The browser says the certificate is invalid
- The domain has only just started pointing to our server and the certificate has not been issued yet. Wait, then check SSL/TLS Certificates in DirectAdmin.
- You are opening an address the certificate does not cover (e.g. an old subdomain). Add it in DirectAdmin and a certificate is issued automatically.
Cloud VPS
On a VPS you install the certificate yourself. The simplest way is certbot: apt install certbot python3-certbot-nginx (or -apache), then certbot --nginx -d yourdomain.com -d www.yourdomain.com. Certbot sets up automatic renewal for you.