Well,
I have this problem too,
First of all Mozilla didn’t trust my site as it say:
“We can’t verify that your connection is secure”
That’s because I don’t have the CA chain,
The browser can’t recognize if my ssl is legit and was issued by a trusted CA.
Second I insert a code to my htaccess and proudly it was trusted!
This actually works, I promise you, my website is on InfinityFree and I have no CA to upload
Okay so use my website on Mozilla or non-modern browser or mini browser like UC mini
Here is my site: amourshipping.gq
Another thing I deleted the code in htaccess and try again on Mozilla and still trusted but when cleared browser data it stops trusting cause the browser has forgot that your site has a legit ssl and put the htaccess code back and trusted back!
Note: your website will still be incomplete without CA chain, this code will ONLY request the CA to verify or validate your websites legit ssl.
Here is the htaccess code:
#Force SSL/TLS (HTTPS)
RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]`