"This page is not working" error on AWS hosted website

Question

I’m setting up hosting a PHP site on an AWS free server, the login home page is showing up correctly, and when I confirm the form login, it goes to the page that checks the login data, and if the data is correct, it goes to the main page, and if something goes wrong it goes back to the login page with the error message by GET, but loading the check page it gives the error of Esta página não está funcionando, I did some tests giving echo in some parts of the code to verify where it is "locking" and I ended up discovering that the error is in the part of connection to the database, which is hosted on Hostgator. Code of the function connecting to the database:

function conectardb(){
        $conexao = mysqli_connect('host', 'usuario', 'senha', 'banco');
        //testar a conexao
        if (mysqli_connect_errno()) {
            echo "FALHA NA CONEXÃO";
        }

        return $conexao;
    }

The above code is on a separate page, but I tried to use on the same page and the error persists. It does not get to print the FALHA NA CONEXÃO in the if.

The same connection code, connecting to the same host of Hostgator is working properly when the site is hosted locally.

I would like to know if anyone has ever been through a similar situation or has any idea how to resolve it, thanks in advance!