Minecraft LAN 'can't reach server

Hi, so me and a friend want to play minecraft together via the 'LAN' setting however (bear in mind we're connected to the same network) can't seem to connect as it says 'can't reach the server' which doesn't make sense because my friend is only downstairs. Although I'm not sure the exact area of LAN I'm pretty sure we can play together if we're within around 15 meters or so away from each other. Can anyone help? We've tried direct connection and everything but this still does not seem to work?