Hi,
It has been observed that the certificates that has been generated by SEPM 12.1.x are using SHA-1 which is cannot be used with chrome and when used with internet explorer or firefox the fisrt 3 tabs gives the error "ntent was blocked because it was not signed by a valid security certificate" since Certificate is not valid
My suggestion would be using Certificates which have SHA-2 or SHA-3 which will be supported by all browsers