It appears Cygwin SSHD's functionality is partially broke in the later
> versions, where SSHD runs as SYSTEM (no longer cyg_server).
> On reboot, any attempt to SSH into the server *before* any previous logon
> attempt (RDP/locally/etc) is quickly denied:
> debug1: Offering public key: /home/<user>/.ssh/id_rsa
> debug3: send_pubkey_test
> debug2: we sent a publickey packet, wait for reply
> Connection closed by <server_addr>
> Once an RDP/local login is attempted, regardless of success/failure,
> subsequent ssh attempts will progress to the password prompt which
> eventually gets us in.
This is a known issue on OS versions older than 8.1.