path: 'admin', component: DashAdminComponent, children: [
  { path: '', component: EstudiantesComponent, pathMatch: 'full' },

<li class="text-center" routerLinkActive="active">
                <a [routerLink]="['estudiantes']">
                    <i class="fa fa-user fa-lg f_1rem"></i>
                    <a class="pb-0 pt-2 pl-3 pl-lg-0">
                        Estudiantes
                    </a>
                </a>
</li>