Hi Rocky,
Initially I followed the same procedure to establish ssl over filebeat-logstash connection, around couple of months back it worked properly, But since a month I am seeing the same errors, in many of my instances. You can check that issue here. This method is using the self signed certificates for the connection, and it is just one side authentication ( not two side ). So firstly, this procedure is not completely safe, but this procedure should work. The errors you faced could be because of the ssl version or cipher mismatch between your filebeat and logstash boxes. The better way is to simply create your own ca, and use its certificates to establish the connection.