I paused the website, logged in to server and deleted all certificates. Then renew the certificates while still pause. That means you can both review the http and https at he same time. http is working https is not. And website is paused. That means it is certainly about server.
Still seeing a 301 redirect to HTTPS, server-side now…
I was working at the test environment, then I found out; if you make the EN language as a second language it starts to loop at the subdirectory rewrite. For example, if you set Russian to the secondary language the /ru can reload successfully even SSL activated. So the problem must only related about the WPML plugin and its Apache communication.
After some tests, I finally fixed the issue. Premium SEO Pack – Wordpress Plugin was responsible for the issue. (It’s 404 redirection tool.)
But I am so happy to see that CloudFlare community is the most helpful community I have ever seen in my 15 years web career. Thank you so much guys.
We try our best, but thanks for the compliments!
Happy everything got sorted!