Uncaught GuzzleHttp\Exception\ConnectException even with catch

Question

sorry to ask a question to which there are already many answers but I followed the suggestions given here Catch Guzzle exceptions on connections refused without being able to solve. I keep getting the PHP error Uncaught GuzzleHttp\Exception\ConnectException even though I added the catch. This is my code:

use \GuzzleHttp\Client;
use \GuzzleHttp\Exception\ConnectException;
use \GuzzleHttp\Exception\RequestException;

and

public function send_post_request( $endpoint, $json ) {
    $http = $this->client;

    try {
        $res = $http->request( 'POST', $endpoint, [
            'verify'  => false,
            'timeout' => 120,
            'json'    => $json
        ] );

        $status = $res->getStatusCode();
        $body   = $res->getBody()->getContents();

        $response = [
            'status' => $status,
            'body'   => json_decode( $body, true )
        ];

        return $response;
    } catch ( ConnectException $e ) {
        $error = [
            'status' => 404,
            'body'   => $e->getMessage(),
        ];

        return $error;
    } catch ( RequestException $e ) {
        $error = [
            'status' => $e->getResponse()->getStatusCode(),
            'body'   => json_decode( $e->getResponse()->getBody(true)->getContents(), true ),
        ];

        return $error;
    } catch ( \Exception $e ) {
        $error = [
            'status' => 0,
            'body'   => $e->getMessage(),
        ];

        return $error;
    }
}

The RequestException is caught correctly instead the ConnectException always results in the error:

Uncaught GuzzleHttp\Exception\ConnectException: cURL error 6: Could not resolve host: ifconfig.me 

or

Uncaught GuzzleHttp\Exception\ConnectException: cURL error 28: Failed to connect to ifconfig.me port 443

Could you please tell me in your opinion what is wrong with the code? Thank you Giulia