The weirdest thing happened to me yesterday. I was transferring a very large file from one computer to another on my network and it took forever. I have both a wired and a wireless connection on my computer, so I tried turning off the wireless network. Suddenly it started transferring way faster. What's going on here?
Most users don’t normally have both a wired and a wireless connection simultaneously, although this can happen if your computer includes both options and you both connect an Ethernet cable while connected to a wireless network.
Normally Windows (and OS X, on a Mac) will use the "best" connection available. But sometimes it will get this wrong and choose the wireless connection over the wired connection. In almost every case, a wireless connection will be significantly slower in transferring information than a wired connection.
Although Windows and OS X both attempt to manage this for you automatically, you can step in and take control over the order of your connections in both operating systems. In Windows, open the Control Panel, and select Network and Sharing Center. Click Change Adapter Settings, click the Alt key to display the menu, choose the Advanced menu, and then the select the Advanced Settings menu. In the Advanced Settings, you’ll see a list of available connections: Ensure that the wired connection appears above the wireless connection, and if not, move it up. Click OK to save the settings.
On a Mac, run the System Preferences application, and select the Network settings. . In the Network settings, beneath the list of interfaces on the left side of the window, click the gear icon, and select Set Service Order. In the Service Order window, drag the wired interface above the wireless interface. Click OK, and then Apply.
In both Windows and OS X, selecting the wired network interface should provide you with better throughput, if it’s available.