I've omitted the bytes on my original post. here is the full message. Right after ServerHelloDone, what appears to be the "client cert" is sent to the server.Something is sent, and it looks like a certificate, but it wasn't requested, and it is not legal for the client to send it.
As I understand it, it is the next action that Client does after ServerHelloDone.It is the next action the client does after CertificateRequest, otherwise it shouldn't do it.
If its the Client cert, why would the client send this (Server did not asked for it)?No idea, ask Microsoft.
If not, what is this data that are being sent and causing EOF?There is no 'data that are being sent and causing EOF'. EOF causes EOF. The client is closing the connection. That causes TCP to send a TCP FIN segment, which means EOF at the receiver.