Susan,
You posted about your problems accessing this KBA on a new thread (out of context) so I am adding a note in this thread on your behalf.
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I can reach that KBA now so I am not able to tell if your access was broken earlier or not. You do need to be able to connect with your SAP Support Id.
If you are using a Certificate that originally worked with prior version (before 12.0.1#3986 or 16.0.0#1695) or if you have had this certificate for a while, then the KBA could explain this behavior.
Otherwise your handshake error is a TLS based one and would need to be investigated.