I am able to connect to a Linux server using Putty via SSH and port 22. About a week ago, I was also able to connect to this server using File Zilla with the same credentials via selecting "SFTP - SSH File Transfer Protocol". For the past two days, I've been having trouble connecting via FileZilla. It seems that it is able to authenticate my username and password, but shortly after, it says "Connection timed out. Could not connect to server". Does anyone know what the problem is? I remember there was a time when I was prompted with some signature key message. I'm not very knowledgeable about keys.