Manually entering a URI with parameters in Angular returns not found

Question

In Angular, when I use the route details/:group using the following line in typescript:

this.router.navigate(['details/', String(group)])

It works perfectly fine. However when I manually refesh the URI (e.g.,http://localhost:4200/details/1), I get the error below.

How do I solve this problem?

My URI routes are

const routes: Routes = [
  { path: '', component: HomescreenComponent },
  { path: 'home', component: HomescreenComponent },
  { path: 'details/:group', component: DetailsComponent }
];