Last month I also bought one of these laptops and had similar issues; if the laptop was more than a few feet away from the router the connection dropped and the laptop reported no networks within range. Despite many hours in trying to resolve the issue to no effect I contacted Samsung helpline and they told me to take it back for a replacement as there was a fault with the laptop. I also carried out some research and this is a well known problem with this series; I took it back and swapped it over for a HP Pavilion g6 which is absolutely fine. Hope this helps.
Samsung Galaxy A8 review: Hands-on