Error: Uncaught (in promise): Error: Cannot match any routes Angular 2

I think that your mistake is in that your route should be product instead of /product.

So more something like

  children: [
  { 
    path: '', 
    component: AboutHomeComponent
   },
   { 
    path: 'product', 
    component: AboutItemComponent 
   }
 ]

I had to use a wildcard route at the end of my routes array.

{ path: '**', redirectTo: 'home' }

And the error was resolved.

For me it worked like the code below. I made a difference between RouterModule.forRoot and RouterModule.forChild. Then in the child define the parent path and in the children array the childs.

parent-routing.module.ts

RouterModule.forRoot([
  {
    path: 'parent',  //parent path, define the component that you imported earlier..
    component: ParentComponent,
  }
]),
RouterModule.forChild([
  {
    path: 'parent', //parent path
    children: [
      {
        path: '', 
        redirectTo: '/parent/childs', //full child path
        pathMatch: 'full'
      },
      {
        path: 'childs', 
        component: ParentChildsComponent,
      },
    ]
  }
])

Hope this helps.