You need to give a relative file path of <a href="https://stackoverflow.com/questions/index.html">Home</a>
Alternately you can specify a link from the root of your site with
<a href="https://stackoverflow.com/pages/en/index.html">Home</a>
.. and . have special meanings in file paths, .. means up one directory and . means current directory.
so <a href="https://stackoverflow.com/questions/4862231/index.html">Home</a> is the same as <a href="https://stackoverflow.com/questions/4862231/./index.html">Home</a>