I found below combination solved the issue:

publicPath: '/Base1/',
devServer: {
    port: port,
    open: true,
    host: '0.0.0.0',
    public: 'x.y.net/Base1/',
    sockHost: 'x.y.net/Base1',
    sockPath: '/Base1/sockjs-node/',   <== this solved the issue
    disableHostCheck: true,
    overlay: {
        warnings: false,
        errors: true
    },