What I did eventually is to change the HTTPS protocol from libCurl to OpenSSL. Also I applied the patch for POODLE vulnerability in SSLv3 (see this thread
) and both the HTTPS/SSL check warning and the
Failed to meet environment requirements
X-Payments Connector callback script https://<new store IP address>/shop/payment/cc_xpc.php is not reachable by X-Payments (check X-Cart logs for details). Your checkout will not work untill you make it accessible by X-Payments. See Troubleshooting for more information. Once you've fixed this issue click here to perform check again.
error message stopped appearing.
I presume that the X-Payments Connector works ok, although I haven't found any 'Test Module' button to run a connectivity test.