CSS not loaded after fresh installation of Drupal 8.2.5

I installed Drupal 8.2.5 successfully on a VPS using LNMP environment.

After installation, the site seems fine and I am not able to login to backend of the site. However, the CSS is not loaded so the site is displayed as plain. I tried to clear caches in backend but no luck to fix the problem.

Anyone has indea to solve the problem? Thank you very much.

Derek

Drupal version: 


Source: https://www.drupal.org/taxonomy/term/22/feed