Issue with new VeriSign certificate clients unable to access website we went from sha 128 to sha-256

One other possible issue to look for with sha-256 is the clients own environment. Validate which OS and browser they are using , our first attempt at sha256 fell foul of a client using an unpatched windows 2003 server.

External link below provides some more info https://casecurity.org/wp-content/uploads/2014/09/SHA-256-Support-List.pdf