Wrong placement of a router can cause a slow Internet. So it very important to place your router in the right location so that you can get a fast internet connection in every corner of your apartment.  Make sure the router is being put in the central location of your apartment.  Make sure there are no other wireless appliances such as baby monitors, cordless phone, garage door openers, Microwave, fridge, etc., near the router.  There should not be many physical obstacles (floors and walls) around your router.  It should be placed as high as you can so that your router can provide better coverage throughout your apartment.