The server has unexpectedly closed the connection

STATUS>             Resolving host "sfs.ibex.co"...

STATUS>             Connecting to "172.22.x.x" on port 22.

STATUS>             Connected to 172.22.x.x:22 from 10.90.36.27:56757.

STATUS>             Negotiating SSH2 session with server...

STATUS>             Client Identification: SSH-2.0-FTP Voyager_16.2.0.328

STATUS>             Server Identification: SSH-2.0-AWS_SFTP_1.1

STATUS>             Initializing key exchange process...

ERROR>              The server has unexpectedly closed the connection.

ERROR>              Could not establish a connection to sftp.

getting the above error, while it is working with the Winscp with same details but not with the FTP Voyager, please help.