CodeIgniter 3.0 Remote Hosting Issue?

I encountered an issue with CodeIgniter 3.0, despite not using it for a while. I've generated views, a controller, and corresponding routes.

Locally, the views display correctly, and the default controller functions as expected based on my setup. However, upon transferring the entire setup to a remote host (a standard shared server with mod rewrite available), problems emerged.

The default controller yields a 404 error, while the custom routes I established result in the message "No input file specified."

I'm unsure how to troubleshoot this, and my hosting provider suggested seeking assistance here. Do you have any insights? Thank you in advance.