Problems curl php and certificate

I try to ask in php curl whith this code on local address

<?php $xstato = $_GET["stato"]; function cambia($stato) { $headers = array( "Accept: application/json", "Content-Type:application/json", "Authorization: Bearer eyJhb...." ); $ch = curl_init(); curl_setopt($ch, CURLOPT_URL, 'http://192.168.1.xxx/things/camera/properties/on'); curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'PUT'); curl_setopt($ch, CURLOPT_POSTFIELDS, "{\"on\":". $stato . "}"); curl_setopt($ch, CURLOPT_HTTPHEADER, $headers); $result = curl_exec($ch); if (curl_errno($ch)) { echo 'Error:' . curl_error($ch); } curl_close($ch); }; ?>

it whork, but if i ask remote address
https://xxxxx.mozilla-iot.org/things/http---w25.local-things-camera/properties/on
return error: Error:SSL certificate problem: unable to get local issuer certificate
what’s missing, where I’m wrong
thanks