PHP CURL从特定服务器到另一个特定服务器无法正常工作

I have two servers s1 and s2. I have a file from s1 trying to access a file from s2 through php curl. The curl commands are written using php in s1/test.php and it is requesting s2/file.php.

I tested if curl is present in s1 and it is working fine with all urls except from s2. Also I can access s2 from localhost but not from s1. Please help me.

Here is my curl code:

$ch = curl_init();
            curl_setopt($ch, CURLOPT_URL, "here the url is placed");
            curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
            curl_setopt($ch, CURLOPT_TIMEOUT, 30);
curl_setopt($ch, CURLOPT_POSTFIELDS, '');
            curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
            $data = curl_exec($ch);
if(!$data)
{
    echo 'Curl error: ' . curl_error($ch);
}
            curl_close($ch);
            echo $data;

When i execute I am getting: "Curl error: couldn't connect to host"

couldn't connect to host means that sonmething is wrong with the connection between the 2 servers. Check DNS's, ip's firewalls, opened ports and services...

What does running wget in the CLI from s1 to s2 says?