a) Check if the certificate has got installed on the server with the private key. Use our SSL Installation Checker.
b) Check what protocols are supported on the server and whether they are compatible with the version of chrome
c) Check if the port is open and configured to accept https request
d) Verify if the public key is matching with the private key
If found the public Key is not matching the privatekey, a fresh CSR has to be generated and certificate has to be re-issued