app.module.ts

...
export class AppModule {
  constructor(router: Router, viewportScroller: ViewportScroller) {
    router.events.pipe(filter((e) => e instanceof Scroll)).subscribe((e: any) => {
      if (e.position) {
        // backward navigation
        setTimeout(() => {
          viewportScroller.scrollToPosition(e.position);
        }, 100);
      } else if (e.anchor) {
        // anchor navigation
        viewportScroller.scrollToAnchor(e.anchor);
      } else {
        // forward navigation
        viewportScroller.scrollToPosition([0, 0]);
      }
    });
  }
}