For networks that require a static IP configuration, you'll need to visit either the IPv4 Settings or the IPv6 Settings pane and select the "Manual" method. (If you're not sure which you're using, you're probably still using IPv4.) Enter the details your connection requires here — your ISP or network administrator can tell you what to enter if you don't know.
If, for some reason, your network only allows devices with a specific MAC address to connect, click the ethernet tab and enter that information into the 'Cloned MAC address' box.
Keep reading for more on checking Wi-Fi drivers and wielding diagnostic tools.
Skip the NetworkManager alternatives
You may be tempted to blame network problems on NetworkManager itself and seek alternative connection tools like Wicd. Wicd was reasonably popular a few years ago, but it hasn't seen an update since April, 2012. If you've gone out of your way to install Wicd or another tool and are experiencing problems with it, you may want to uninstall it and re-enable NetworkManager.
Hardcore Linux geeks may want to ditch NetworkManager and go back to the old-fashioned way of configuring network connections by hand. But even a hardcore, penguin-loving Linux geek can save time with the automatic configuration NetworkManager provides.
Make sure you're using the right Wi-Fi drivers
Ubuntu and other Linux distributions include a variety of open-source drivers that support most Wi-Fi and wired ethernet hardware built into laptops and desktop PCs. You shouldn't have to install any drivers in most cases. After installing Ubuntu or even booting up an Ubuntu live CD or USB drive, your hardware should be detected automatically.
Some wireless network hardware still requires a proprietary, closed-source driver provided by its manufacturer, or a special firmware file you'll have to install. You can check to see if your hardware is supported by the Linux kernel before looking for proprietary drivers. Ubuntu tries to make this easy by providing a driver installation tool that will quickly install and enable these third-party drivers.
If Wi-Fi isn't working in Ubuntu, click the gear icon at the top-right corner of the desktop, select System Settings, click the Software & Updates icon, and click the Additional Drivers tab.
Ubuntu will scan your system's hardware and show any alternate drivers you can use. Many of these files come on Ubuntu's installation media, so they can be installed even if you don't have an Internet connection.
If that doesn't work, perform a web search for your computer's name and model number or your Wi-Fi hardware's name and "Wi-Fi Ubuntu," or something similar. You can often find fixes for specific hardware in forums.
USB modems and Wi-Fi dongles can be harder to set up. You may have to search for your specific USB device and see if there are any tweaks or drivers available.
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