Trouble Connecting to Remote

Too many authentication failures

1. mv ~/.ssh/config ~/.ssh/c

Restart the Mac

Yes, actually this fixed it for me when nothing else here would.

Reinstall the SSH key

1. Make sure the value for Host in ~/.ssh/config on your local matches the remote IP or domain.
2. Make sure the IdentityFile exists.
3. Paste the contents of .pub of the IndentiyFile to the remote authorized_keys
4. Update permissions on remote and local i.e., chmod 0700 ~/.ssh;chmod 0600 ~/.ssh/*;chmod 0644 ~/.ssh/*.pub

Mitigation Options

Force login using password

1. Add this to the ssh: -o PreferredAuthentications=password
2. Enter the password to see if you can connect that way. If so the issue is with the certificate.