How can I fix these SockJS ssl errors?

This was a struggle, but it's working now...

Add a public property to the devServer object in vue.config.

The property I needed was public, not publicPath, and the clincher was learning that vue will ignore config changes in configureWebpack{ devServer: {. You need to use the top level devServer property.

So my working vue.config.js is...

module.exports = {
  baseUrl: process.env.NODE_ENV === 'production'
    ? '/production-sub-path/'
    : '\/mobileapp\/v\/',
    devServer :{
      public : 'notilusdev.dimosoftware.com',
      host : '0.0.0.0',
      disableHostCheck : true
    }  
}

Then I needed to reverse-proxy https and wss:// requests through express, terminating the ssl in express, but that's another story.