Exchange ActiveSync Monitor fails with read:errno=104

That error 104 is basically given back when the remote end closes the connection on you... You'll get back something similar if you use curl as well (Using curl saves typing all those headers, but you can get more control with openssl utility).

I take it the openssl connection is made and you get a valid SSL session established before you move to entering the "GET... " request and headers. That would indicate that the server is running and listening, accepting the connection and negotiating the SSL, but is unwilling or unable to respond (And unable to simply return a 500 error either. It's just closing the connection without actually responding).

Try & get a view of the logs at the CAS server... There should be info in there as to what's happening...

H