a) Try adding the website the trusted site in Internet options and check
b) Clear the SSL state and verify
c) Check whether the port is opened for incoming and outgoing requests with the network team.
d) Please confirm if the certificate has been installed properly. Use our SSL Checker tool to verify that.
e) Enable all the protocols in the advanced option including SSLv3 and SSLv2.
f) Please try accessing the website using some other machine or browser. If yes, try to reset the Internet explorer and check. If No, please check contact the Website owner/ Network team.
g) Please check the System Date and Time.
Try accessing the website using the Public IP and check if the website is opening (Certificate Name Mismatch Error will Pop up). If yes, then check if DNS mapping has happened with the Ip Address.