Sounds like an Oracle issue from what I could find with Google.
"NZE-28862: SSL connection failed
Cause: This error occurred because the peer closed the connection.
Action: Enable Oracle Net tracing on both sides and examine the trace output. Contact Oracle Customer support with the trace output."
For further details you may refer the Note: 244527.1 - Explanation of "SSL call to NZ function nzos_Handshake failed" error codes
There is unfortunately not much you can do on ACE.
You could try the following, but I have no idea if it will help or not
AceC6k2/Admin(config-probe-https)# connection term ?
forced Specifies forced TCP connection termination
AceC6k2/Admin(config-probe-https)# connection term forced
Gilles.