I also found that when proxying with nginx I had to completely stop and restart serving the app in dev mode to make changes to sockPath.

I have this working. Edit quasar.config.js and add to the devServer: {} block your desired path. In the example below I want the app served from /admin

build: {
  vueRouterMode: 'hash, // available values: 'hash', 'history'
  publicPath: '/admin',
  ....
},

devServer: {
    sockPath: '/admin/sockjs-node',
    ....
}