SFTP - 'Algorithm negotiation fail'

I am facing issue while using the SSH Key Pair authentication for SFTP. So when I am trying using Basic Credentials, I am able to establish the connection with Remote Directory and able to Send and Receive File. But for same username when I am trying through SSH Key Pair authentication I am getting error as ".filetransfer.sftp.SendFileOverSFTP - com.jcraft.jsch.JSchException: Algorithm negotiation fail".

I have created Third-Party Credentials in Appian using the username only and uploaded the private key along with a constant associated with it.

Here is my File Transfer Configurations CDT:

'type!{plugins.ps.appiancorp.com/.../}FT_Config'(

serverHostName: "xyz.com",

serverPort: 22,

scsExternalSystemKey: "aws-cmd",

usePerUserCredentials: false(),

privateKeyFile: cons!MS_SFTP_USER_PRIVATE_KEY_FILE

)