Whenever an Ethernet adapter is installed, it's good to make a quick check that they have been recognized and the drivers are installed. This may not be easy to do with some devices like networked printers (which is fine since those are usually installed and tested at the factory), but for Windows-based PCs, there are some easy tests that can be done. If you can't get similar successful results to those you will see in this section, then your Ethernet card/port/adapter is not properly installed or the drivers it relies are not properly installed. You'll likely just be wasting your time to even try to go on. These tests are simple, but it's also essential that your Ethernet ports pass.
It's a good idea to do this test even if you have a built-in Ethernet port that you know is there. Software driver upgrades have been known to cause issues and break working systems. I have a laptop that attempts to conserve battery life by turning off the power to the wired Ethernet port when it's running on the battery. If there isn't a wired Ethernet connection up when I unplug the AC power, it shuts the port off. The bad thing is it doesn't turn the port back on when inserting a cable thereafter so long as it remains on battery. (There's a Control Panel in my particular case that will let me re-enable the wired Ethernet port.) Other laptops have a physical switch that turns off the wireless Ethernet adapter. These can get switched by accident. Suffice it to say there are cases where an Ethernet adapter may not be recognized even when you know it is (or was) there.
The first test is to just verify that the Ethernet port is recognized by your operating system. The graphics in this section were taken from a mix of Windows 2000, XP and Vista, Windows 7, and Windows 10 machines. (That gives you an idea just how long this has been an issue, too.) In most of the tests, the various flavors of Windows machines have the same tools with a slightly different look.
Even if your Windows computer came with an Ethernet port pre-installed or built-in, it's good to make these checks. Occasionally, manufacturers forget to install the drivers for some of their devices and sometimes a driver installed for some completely different device can interfere with the LAN driver. Lately, this occurs most often when performing a major upgrade (such as upgrading from Windows 7 to Windows 10).
For Windows 10, click on the Start button (typically in the lower-left corner), and type device manager into the search box. Choose the Device Manager Control Panel from the list.
In Windows 7, Start by right-clicking on the My Computer icon and choosing Properties from the pop-up menu as shown above. On Windows 8 and 8.1 systems, if you don't have a My Computer icon, right-click on the name of your computer in any file explorer window and pick Properties from there.
In Windows XP, the System Properties dialog window will appear as shown to the right. Click on the Hardware tab and then the Device Manager button.
For Vista and Windows 7, start by right-clicking on the Computer menu item from the Start menu. Then choose Properties from the pop-up menu.
In Vista and Windows 7, the Control Panel -> System Properties dialog window will appear instead as shown below. Next, click on the Device Manager link.
Regardless of the operating system path that brought you here, the Device Manager dialog window should now be displayed. It is roughly the same for all versions of Windows.
If your Ethernet adapter is recognized as a device by the operating system, it will appear under the Network adapters portion of the Device Manager list. (By default, the devices are listed alphabetically by type.) If you see Network adapters listed, click on the little plus sign next to it to expand that entry. You could see your specific Ethernet card (NIC) listed there as shown below. If you don't see such an entry, see Problem 1: There isn't any entry named "Network adapters" in the Device Manager or there is no entry in the Network adapters that corresponds to my Ethernet adapter. (Note: In the words of the Jedi master, "The 1394 Net Adapter is not the device you're looking for.")
Right-click on the entry for your card (e.g., Linksys EtherFast) and choose Properties from the pop-up menu. (You can also just double-click on the entry.)
The properties for your Ethernet adapter should look similar to the one below. Pay particular attention to the line that reads, "This device is working properly." This is what we want it to read.
Problem 1: There isn't any entry named "Network adapters" in the Device Manager or there is no entry in the Network adapters that corresponds to my Ethernet adapter
The usual culprit when you know you have the Ethernet adapter installed, but it doesn't show up under the Network adapters list is a bad or missing driver. Look in the Device Manager for the Other devices entry. (In general, you should not have any devices listed in the Other devices entry if all devices are installed properly on your PC.) If there is one, expand it by clicking on the plus sign. If you see a device named like "PCI Ethernet Controller," it's almost guaranteed you have a (lack of a) driver problem. Possible solutions:
- Uninstall the device and let it be rediscovered upon reboot.
- Get the latest drivers from the manufacturer. (Make sure you know the exact manufacturer, model number, and version of your card. I used to use a number of Linksys LNE100TX cards and there were three or four versions of that model. Each uses a different driver.)
What you want this field to say is "This device is working properly." If you have any other message there, you likely have a wrong, corrupted, or missing driver. Microsoft has a nice list of the device manager error codes here along with some suggested solutions.