Eugene's observations

It is common for devices to be able to connect with a network either through Wi-Fi or Ethernet.  Given that a hard wired Ethernet cable has a theoretical speed of twice Wi-Fi, it make sense to ensure you are passing data over the fastest available connector.  To set the priority of Ethernet over Wi-Fi proceed as follows.

For Apple Mac OS X open Network Preferences.  From the cog at the bottom left choose Set Service Order... Now drag Ethernet to the top of the list.  Click OK then click the Apply button. 

For Windows 8 open Control Panel > Network and Sharing Center  > Change adapter settings.  If Always show menus is not set in the Folder Options then press the Alt key to get the menu.  Choose Advanced > Advances Settings...  and in the Adapters and Bindings tab select Ethernet and click the up arrow to get it to the top of the list.  OK.

For Linux it varies a lot sepending on which distro you have.  Editing /etc/network/interfaces to reduce the network that should have highest priority is a common method on many.  FOr others the ifconfig command allws metrick adjustment.