Angular 4 Lazy loading with named router-outlet not working

This is known bug, you can track the issue here

The workaround or we can say solution to this issue is, use non-empty paths for your top
level routes if auxilary(i.e. named) routes exist in a lazy loaded module.

The only flaw I can see is, an additional url segment added in routes

MainRoutingModule: Top level non-empty path(i.e. “path: ‘load'”)

import { ModuleWithProviders, NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';

import { MainpageComponent } from './mainpage.component';
import { ProductComponent } from './product.component';
import { ProductDetailComponent } from './productdetail.component';

const childroutes: Routes = [

 { path: 'load', component: MainpageComponent  ,
    children: [ 
      {path: 'product', component: ProductComponent
      {path: 'productdetail', component: ProductDetailComponent,
        outlet: 'detail' 
      },

    ]
 },


];

export const routing: ModuleWithProviders = RouterModule.forChild(childroutes);

const newLocal: NgModule = {
    imports: [RouterModule.forChild(childroutes) ],
    exports: [RouterModule, ],
    declarations: []
};

@NgModule(newLocal)


export class MainRoutingModule { }

MainpageComponent:The correct syntax to use the secondary routes.

[routerLink]=”[{outlets:{detail:[‘productdetail’]}}]”

import { Component, OnInit, ViewEncapsulation } from '@angular/core';
import { Router } from '@angular/router';

@Component({
  selector: 'app-main',
  template: `
  <div>

  <div><a [routerLink]="['product']"> Product </a> </div>
  <div><a [routerLink]="[{outlets:{detail:['productdetail']}}]"> Product Detail </a> </div>
  <div> <router-outlet></router-outlet></div>
  <div> <router-outlet name="detail"></router-outlet>

</div>
  `,
  encapsulation: ViewEncapsulation.None,
})

export class MainpageComponent {}

LoginComponent:

Use [routerLink]=”[‘mainpage/load’]” to load the main module.

import { Component, OnInit, OnDestroy } from '@angular/core';

@Component({
  selector: 'app-login',
  template: `This is login page place holder <br> <a [routerLink]="['mainpage/load']">Go to Main Page</a>`,

})

export class LoginComponent implements Oninit, OnDestroy {
constructor() {}

ngOnInit(): void {}

}

Demo:https://plnkr.co/edit/0ZpNL3lvbRbexLzQqRZh?p=preview