You subscribed to a high-speed internet plan (300MB, 500MB, or 1GB), but Windows insists on limiting your connection to 100Mbps?
If you've already searched the Microsoft Community and haven't found the answer: you're not alone . The bug that blocks speed negotiation on Realtek PCIe GbE cards is old, but it persists.
We tested and validated: this method worked on Windows 10 Pro (21H2) and continues to work perfectly even on the latest Windows 11 (25H2).
🛑 Essential Checklist: The Hardware
Before tinkering with the settings, we need to ensure your equipment supports the speed. There's no point in modifying the system if the bottleneck is physical.
- Suitable Network Cable: The use of standard CAT5e or higher cables is mandatory (CAT6 is ideal). Older CAT5 cables are physically limited to 100Mbps.
- Gigabit Network Card: Your motherboard must support 10/100/1000 Mbps (Gigabit Ethernet). Older "Fast Ethernet" cards do not exceed 100 Mbps.
- Router Port: The port where the cable connects to the router also needs to be Gigabit. Some devices have mixed ports.
🔧 The Procedure (Step by Step)
After several tests, we developed the exact procedure that forces the board to negotiate the correct speed. Follow carefully:
- In the taskbar, right-click the network icon and select "Network and Internet settings" .
- Go to "Advanced network settings" > "More network adapter options" (Windows 11) or "Change adapter options" (Windows 10).
- Locate your wired (Ethernet) connection. Right-click and select Properties .
- Click the Configure... button (right below the Realtek card name).
- Go to the Advanced tab.
- In the list on the left, look for Speed & Duplex.
- In the "Value" menu on the right, change to Auto Negotiation .
⚠️ THE CAT'S LEAP (Crucial):
Once you click OK to confirm the change, disconnect the network cable from your PC immediately .
Wait approximately 2 seconds and reconnect the cable. This physical reconnection forces the driver to clear the old negotiation cache and recognize the modem's actual speed.
☢️ Nuclear Method (If nothing works)
If the problem persists, there may be a corrupted driver interfering with the system.
- Disconnect the network cable.
- Open Device Manager > Network adapters.
- Right-click on the Realtek card and select Uninstall device (check the option to delete the driver).
- Restart your computer.
- Install the official drivers downloaded from your motherboard manufacturer's website.
- Repeat the Auto Negotiation procedure listed above.