FileZilla reports "Unknown Host Key" | "Hostkey algorithm: ecdsa-sha2-nistp521 521" then allows me to connect.
var ftp = new Sftp();
ftp.Settings.SshParameters.PreferredHostKeyAlgorithm = SshHostKeyAlgorithm.ECDsaNistP521;
ftp.Connect("host", serverPort: 22);
ftp.Login("user", "password");
var validated = ftp.PutFile(uploadFileName, $"/inbound/{Parse.FileNamePart(uploadFileName)}") == new FileInfo(uploadFileName).Length;
ftp.Disconnect();
Note that I've purchased your latest Sftp version today (I've been a client since 2012), but still can't connect. Thanks.