Force all links to be absolute
Have a look at this module: Pathologic


  Pathologic is an input filter which can correct paths in links and
  images in your Drupal content in situations which would otherwise
  cause them to “break;” for example, if the URL of the site changes, or
  the content was moved to a different server. Pathologic can also solve
  the problem of missing images and broken links in your site’s RSS
  feeds. See more example use cases on the documentation page.