Component Navs bug??

I am using bootstrap v4.0 with angular, but I meet some problems about component navs like this:

---

Firstly, I navigate to ‘help’, it works fine, current url is http://localhost:4201/help.

But if I refresh the whole page, I get this(same url):

This is my code:

<ul class="nav nav-tabs justify-content-end">
  <li class="nav-item">
    <a class="nav-link active" routerLink="/index" routerLinkActive="active">Introduction</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" routerLink="/analysis" routerLinkActive="active">Analysis</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" routerLink="/help" routerLinkActive="active">Help</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" routerLink="/fqa" routerLinkActive="active">FQAs</a>
  </li>
</ul>

Is it a bug or I use it with a wrong way??

[OnlyBelter]

@sarbull Thanks, that’s my fault.

[XhmikosR]

@OnlyBelter: why are you using active for all nav-links?