Redirect to 404 page if url is incorrect or if a 404 error is got from BE

Question

I need to redirect to a custom page in case if the entered URl does not exist or in case if I receive a 404 error from BE. To catch the BE error I do a navigation in the Interceptor to the /error page, but how I should proceed with the incorrect URL?

This is what I did:

  <IntlProvider translations={translations} locale={locale}>
      <Router>
        <Switch>
          <Route path="/error" component={CustomErrorPage} />
          <Route exact path="*" component={CustomErrorPage} />
          <PrivateRoute path="/" component={Main} />
        </Switch>
      </Router>
    </IntlProvider>

PrivateRoute checks if the user is logged in. If anybody has an advice it will be nice. Thanks in advance!