Sometimes the Cmder SSH agent seems to be borked and anything you try to connect to just rejects. I often run into this when running an Ansible command on a remote host
ssh firstname.lastname@example.org email@example.com: Permission denied (publickey). ssh_exchange_identification: Connection closed by remote host
Just kill the
ssh-agent.exe processes (Task Manager works just fine),
Then restart the SSH agent,
$ start-ssh-agent Removing old ssh-agent sockets Starting ssh-agent: done
This does not work with the latest versions of Cmder.