Drupal Commerce Paypal WPS - Connection refused
This was an environmental problem. The Drupal server did not have a direct connection to the internet. Setting the proxy settings in settings.php got this to work.

http://devincarlson.ca/blog/configuring-drupal-use-proxy-server-when-making-external-http-requests

In my case the settings I had to set were:

$conf['proxy_server'] = 'my server';
$conf['proxy_port'] = 1234; // port number