The SSL Configuration Generator is a good starting point. Select your HTTPS server and select a Intermediate or even better a Modern configuration.

Copy the SSL configuration into your HTTP server setup and restart your HTTP server.

Check your new SSL configuration:

• https://cryptcheck.fr
• https://www.ssllabs.com/ssltest/analyze.html .. goto "Configuration" section

Don't forget to "reload/clear-cache" if changed your SSL configuration and restarted the HTTP server.

Warning
If your settings don't take effect .. they might be overwritten somewhere else in the HTTP configuration. Some SSL tools like cerbot tend to overwrite settings in the common used configuration file.

cerbot / letsencrypt

Do you have cerbot (letsencrypt)? look out for a include directive:

include /etc/letsencrypt/options-ssl-nginx.conf

This file contains the SSL options that Certbot thinks are optimal, but they are a bit outdated.

.. we can't speak for all HTTPs servers but we have seen this issue in Apache and NGINX