Firstly, Thank you all for your help.
A few months ago, I changed a new share web hosting, it is a Apache server with Nginx reverse proxy in front. When I use Cloudflare, I get “Too Many Redirect” error immediately. After some searching, I found out that changing the SSL setting in Cloudflare from “Flexible” to “Full” solved the problem.
However, after few month, Let’s Encrypt SSL Cert expired and it cannot renew itself. After some searching, people said SSL setting in Cloudflare set to “Full” stop Let’s Encrypt renewing the Cert.
Now, this is my question.
If I set SSL setting in Cloudflare to “Flexible”, I get “Too Many Redirect” error immediately.
If I set SSL setting in Cloudflare to “Full”, Let’s Encrypt SSL Cert cannot renew.
So, What should I do to solve both problems together?
Finally, Thank you all for your help.