LibGit2Sharp SSH, Unable to exchange encryption keys

Question

Trying to put together a sample project cloning a repository (hosted in GOGS) using SSH and am getting the following error:

Failed to start SSH session: Unable to exchange encryption keys

I'm on windows, the keys are generated using ssh-keygen, and I have the following nuget packages referenced

• LibGit2Sharp 0.25.3
• LibGit2Sharp.NativeBinaries 1.0.235
• LibGit2Sharp-SSH 1.0.22
• LibGit2Sharp-SSH.NativeBinaries 1.0.14

We're able to pull files from a test bit bucket account, but not from the GOGS repository url, using code like the following (the same keys have been uploaded to both accounts).

var co = new CloneOptions
{
        CredentialsProvider = (_url, _user, _cred) => new SshUserKeyCredentials()
        {
                PrivateKey = @"C:\Users\username\.ssh\keygen\gen",
                PublicKey = @"C:\Users\username\.ssh\keygen\gen.pub",
                Passphrase = string.Empty,
                Username = "git"

        },
};
Repository.Clone("ssh://git@<site_url>:443/Project/Project.git ", TestPath, co);

I'd also add that we can clone from both urls using a variety of git clients (git exe, tortoise git, gitkraken) without issue. Also we can connect over https with username and password with LibGit2Sharp.

Things I've tried so far:

1. Generating new keys with ssh-keygen
2. Converting the private key file to openssh using puttygen > Conversions > Export OpenSSH
3. Converting the private key to PEM format using "openssl rsa -in key-out key.pem"
4. Made sure that the Public key was single line, starting with type, followed by base64 key, no comment at the end