Workbench no longer connecting to AWS RDS (no replies)

I get an error message when I run workbench:

CANNOT CONNECT TO MYSQL SERVER.

Workbench 6.2.5.0 use to work fine. But I have not used it in a few months. Now it will not connect.

My MobaXterm connects to AWS just fine.

All of my PHP programs on my AWS EC2 instance are running just fine.

So I know that port 3306 is not blocked and that MySQL is running on my AWS EC2 instance.

It is only the Workbench that will not connect.

Any help would be appreciated.