User Agent is: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/68.0.3440.106 Chrome/68.0.3440.106 Safari/537.36.
Well, first of all you need a section to link to - in your code I can’t see enough content to actually jump to.
Let’s take one of your links as an example:
<a class="nav-link" href="#About us">
Please be aware that you should avoid special characters in your anchors - in your case the space in “#About us”. I would suggest to follow camel case with this: “#AboutUs”, but this depends on how you want to manage naming.
Then you need a section to jump to, for example:
<section id="AboutUs">
<!--- Your Content --->
</section>