You’re right those are the first two results and I noticed them first time I looked into your issue. The bug in the first search result has been resolved. Let’s settle this once and for all, try using a different client. FileZilla I recommend downloading the zip version so it’s portable and doesn’t have to be installed for testing.
If if you still receive the same error message with FileZilla. I would assume that something server-side. Taking the shotgun approach I would MineOS reimage your server and regenerate a RSA keypair.