SOAP not working when I hook on "wp_loaded"

I can make SOAP calls from by example the woocommerce_payment_complete hook or from the WP CLI.

If I make the exact same call from wp_loaded I get the SOAP Error: failed to load external entity

Is it bad practice to hook on wp_loaded? I understood that wordpress was fully loaded, I do this to receive callbacks from an external service but there's maybe a better way to do it? (I'm pretty new to Wordpress development).

add_action('wp_loaded', function() {
    $uri = explode('?', $_SERVER['REQUEST_URI'])[0];
    if ($uri == '/navision') {
        $payload = file_get_contents('php://input');
        _navision_callback_received($payload);
    }
});

add_action('woocommerce_payment_complete', '_woocommerce_processing_order', 10, 1);

function _navision_callback_received($data) {
  /* SOAP CALL ---- error */
}

function _woocommerce_processing_order($orderId) {
 /* SOAP CALL ---- success */
}