Angular Routing with wildcards not always working

Using Angular 4, I have the following in my Routes collection:

{
    path:"**",  //wildcard
    component: NotFoundComponent,
}

and if I try to navigate to http://127.0.0.1:8000/xxx I get correctly routed to my NotFoundComponent, however if I try to navigate to http://127.0.0.1:8000/xxx_(xxx) I do not. I've tried various permutations of

{
    path:"**_(**)",  
    component: NotFoundComponent,
},

placed prior to my wildcard path, but they haven't worked either. Thoughts?