PuTTY Fatal Error: expected key exchange group packet from server

Hi all,

I have a Laravel project running on a Digital Ocen droplet which I set up using Forge. I am a Windows user.

I recently destroyed the droplet and created a new one. On the old droplet I was able to use PuTTY to log in to Ubuntu on the droplet. To do this I followed these instructions:

1> Use PuTTY to create a public and private key.

2> Use Forge to add the public key to the droplet.

3> In Putty enter the IP address of the droplet.

3> In PuTTY on the Data tab enter the default username (which is 'forge' by default).

5> In PuTTY on the Connection->SSH-Auth tab browse to find the private key.

6> Open the session using PuTTY.

This worked on my previous droplet. I still have the PuTTY connection data saved in PuTTY even though the droplet itself was destroyed so I was able to double-check all the settings, they are identical to the settings that I have added for the connection to the new droplet.

When I try to connect using PuTTY I see the following error:

PuTTY Fatal Error: expected key exchange group packet from server

I also have WinSCP on my Windows machine and using the same public/private key I AM successfully able to access the droplet so I know the key pair is working and that the IP address and username are valid.

I can't find anything online about this so its driving me crazy. :(

Any ideas?

Regards, David