FTP Connection issues

Had an sftp connection that has been working fine for a couple of years. The Co i am connecting to made some changes on their end and now the connection is broke. I have double check my connection information and it is still correct. the message i am getting when i test the connection is "Exception of type 'EnterpriseDT.Net.Ssh.Routrek.SSHC.SSHException' was thrown.
any help would be awesome

this is also a message i have seen
"The negotiation of key exchange method has failed"

Thanks