SecureBlackbox .NET: SFTP connectivity issue with some "SSHD" server
The issue happens only in applications running .NET 4.5 and using SecureBlackbox .NET edition.
The error is caused by the bug in server's implementation of 3DES algorithm. While the server declares that this algorithm is supported, in fact it's not. And the client negotiates this algorithm when it's enabled. The solution is trivial - disable 3DES algorithm when connecting to such server. This is done using EncryptionAlgorithms property of the client component.
Unfortunately automatic disabling is not possible as there exists many server versions that name themselves "SSHD".