After doing some more tests I found that the problem with my site failing to load on the Android Firefox happens when the site is loaded for the first time after restarting NGINX.
Steps to reproduce:
1. Restart nginx service
2. Try to load my site with Android Firefox browser.
3. Get secure connection failed error (MOZILLA_PKIX_ERROR_REQUIRED_TLS_FEATURE_MISSING).
4. Refresh the page.
5. Site loads. Now everything works normally until nginx service is restarted again.
The problem I am having sounds very similar to this one:
https://community.letsencrypt.org/t/ocsp-stapling-issue-with-nginx/119238
I'm not sure if it's the same problem affecting the
https://webinoly.com site or not. That is still not loading at all on Firefox (Android and Chrome) even with multiple page refreshes.