Gigabit Internet Showing Up as 100MB

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Setting up a home or small office network no longer requires a specialist technician to constantly monitor and optimize the LAN routers and connected PCs. As Windows networking has improved and new features have became available on the hardware, configuring a 1GB network should be as simple as connecting the LAN to a router that came with this capability. If however the network’s rated speed only gives 100MB, troubleshooting the issue is more complex. To find the problem, you’ll need to check the hardware devices, cable connections, and the software you are using to connect and manage the network.

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100MB LAN Network

If your Gigabit internet on the LAN connection is showing up as 100MB instead, you’ll need to diagnose the problem in a series of steps. The first is to ensure your LAN Adapter supports speeds of 1GB, but if it worked previously that could mean it’s a hardware problem.

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Troubleshooting 100MB Network on 1GB Adapter and Router

Modern networks provide fast and secure access to internal networks and the internet. If your network speed previously worked on 1GB transfer rates, but suddenly only provides 100MB it could point to your hardware. Every piece in the network can influence the speed you’re getting from the PC itself, all the way to the router that provides access to the internet. To start fixing the issue, you’ll need to check the physical components first.

Physical Network Cable Checks

Network cables can be the cause of your issue. The quickest way to check if your network cable is the culprit is to test your connection with a different cable. A faulty cable can lead to connectivity, continuity, and performance issues.

The network jacks on both ends of the cable can also be the cause of the issue, as well as any damage between the connections. To verify the cable isn’t faulty, follow the steps below.

  1. Check both connection jacks to see if it has any loose or frayed wires. If any of the wires are loose, it can be the cause of the performance issue. You should replace the cable if you discover damage to the connectors.
  2. Inspect the entire length of the cable and check if the harness shows any clear signs of damage. A bent or damaged cable can reduce the amount of information it’s capable of transferring between the PC and LAN router. If you find any damage on the cable, replace it to restore your network speed.
  3. Is the cable capable of transferring 1GB speeds? Different network cables support different network speeds. A Cat-5 cable will only provide 100MB transfers, while a Cat-5e or Cat-6 can support up to 10GB transfers. Check the cable’s labels to make sure you are using a Cat-5e or higher rated data cable.
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Check Cable Rating

Troubleshooting the Network Configuration and Properties

If you’ve verified that the cable isn’t responsible for the reduced performance, you’ll need to check the network configuration, adapter properties, and router settings. Changes to any of these settings can lead to a reduction in transfer speeds.

Troubleshoot the Issue with Windows Troubleshooter

To check if your adapter is working properly, you can use Window’s built-in troubleshooters.

  1. Hit the Windows Key and type Control Panel. Then select the top result.

Open Control Panel

  1. If your Control Panel shows the Category View, change it to display Small Icons instead.
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Change Category View

  1. From the list of available applications, select Network and Sharing Center.
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Open Network and Sharing Center

  1. In your Network and Sharing Center, you can see the active network, set up a new network connection, troubleshoot problems, or change your adapter settings. Before making changes to your device properties, you can let Windows run a troubleshooter on your adapters to see if it can automatically fix your connection issues.
  2. Click on Troubleshoot Problems from the Change Your Network Settings section.
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Troubleshoot Problems

  1. In the Troubleshooter Application, scroll down and find the Network Adapter option.
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Troubleshoot Network Adapters

  1. Click on Run Troubleshooter to let Windows check your network adapter’s configuration for any issues.
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Run Troubleshooter

  1. Select the Ethernet Adapter you’re currently using from the list and click Next to proceed.
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Select Ethernet Adapter

Note that for PCs with only one network adapter, the troubleshooter will automatically run on that adapter and you won’t have to pick an adapter from the list.

  1. Wait for the process to complete and check the results. If Windows detects any issues, it will recommend a fix. However, if the configuration of your network adapters does not have any problems, you’ll see a message that Windows couldn’t detect any problems.
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Resolving Problems

  1. If there are any issues with the cable, the troubleshooter will detect the connection issue and request you replace the cable and connect it to your PC.
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Cable Broken or Damaged

  1. It can occur that even after inspecting the cable and you didn’t find any visible damage on the housing or connectors, it could still be faulty. Replace the cable with a new one and rerun the troubleshooter to see if the cable is working as required.
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Verify Adapter Settings for 1GB Speeds

If you’ve run the troubleshooter and received a Windows Couldn’t Detect Any Issues result, you’ll need to verify your adapter’s speed settings.

  1. In your Network and Sharing Center, select the Change Adapter Settings option from the left menu.
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Select Change Adapter Settings

  1. On the list of adapters, choose the one you’re using and click the Right Hand Mouse Button (RHMB) to open the context menu.
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Open Adapter Context Menu

  1. Select Properties from the Context Menu to access your adapter’s settings.
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Open Adapter Properties

  1. On the Ethernet Properties window, you can enable or disable different features and install additional protocols. To change the device settings, click on Configure to continue.
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Select Configure Device

  1. This will open the Device Controller Properties window where you can check the status, make changes to the settings, find out information about the driver, or check historical events on the device. Select the Advanced tab to access the device settings.
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Select Advanced Tab

Note that you should also check the Device Status to make sure it’s working properly.

  1. On the Advanced tab, locate the Speed and Duplex setting.
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Locate Speed and Duplex Setting

  1. The Auto-Negotiation option may cause network performance issues on certain Ethernet adapters and routers. The setting allows your adapter to change the speed settings according to the LAN configuration you connect to your PC. If you connect to different LAN networks regularly with different speeds, it can occur that the setting doesn’t update from 100MB to 1GB while switching.
  2. Change the Value to match the network speed of the LAN you’re connecting to your PC and use the manual speed setting.
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Select 1GB Full Duplex

  1. Click OK to apply the setting and test your network performance. If your adapter doesn’t have the 1GB setting available but you know the rating should go up to that speed, it could indicate that you aren’t using the right driver for the device.

Update LAN Adapter Device Driver

If you don’t have the setting available or the device still only provides 100MB speeds after changing the Speed setting to a manual value, you may have to update the driver for the device.

  1. On the Ethernet Properties Window, once again click on Configure to access the Device Properties Window. Then select the Driver Tab to access your driver details.
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Select Driver Tab

  1. Select Update Driver from the available options.
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Update Adapter Driver

  1. On the Update Driver window, select the option to let Windows Search Automatically for Updated Driver Software.
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Automatically Update Drivers

  1. Windows will connect to the internet and search for the latest drivers online. If a newer driver exists, Windows will download and install the driver for you. If you’re using the latest driver, Windows will inform you that no updated drivers are available.

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With Driver Support, you won’t have to troubleshoot performance issues on your LAN adapters manually. Driver Support will inventory your PC’s hardware and ensure you use the latest drivers for all your devices. After downloading and registering the application, it will automatically keep your PC up to date and improve your performance.

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