...When choosing a custom port, you need to find one that is not already in use. You should not choose one that is being used by webpack-dev-server / devServer or any other process. Instead, pick one that is only for webpack-dashboard and pair that up in the plugin configuration and CLI port flag. We've standardized our local development process for webpack-dashboard on using yarn. We recommend using yarn 1.10.x+, as these versions include the integrity checksum. The checksum helps to verify the integrity of an installed package before its code is executed. ...