ethernet doesnt go higher than 100Mbps even tough the aggregated link speed is 1gig

Understanding Why Your Ethernet Connection Isn’t Surpassing 100 Mbps Despite a 1 Gbps Link Speed

Introduction

Many users encounter a common networking issue: their Ethernet connection fails to exceed 100 Mbps, even when their equipment and configuration suggest otherwise. If you’re experiencing this problem, it can be frustrating, especially when your network hardware indicates a gigabit link, yet your actual transfer speeds are limited. This article aims to explore the possible causes and solutions to this problem, ensuring you can achieve optimal Ethernet performance on your PC.

Identifying the Problem

Suppose your PC is equipped with a Realtek PCIe GbE Family Controller or a similar gigabit Ethernet adapter, and your network hardware supports gigabit speeds. Despite this, your transfer rates remain capped at 100 Mbps. Notably, other devices connected to the same network—such as your Xbox connected directly to the router—can achieve the expected speeds of up to 500 Mbps or more.

Common indicators include:

• Ethernet link speed showing as 1 Gbps in network properties or device manager.
• Actual data transfer rates restricted to approximately 100 Mbps.
• Verified that all Ethernet cables are Category 6 (Cat6), which supports gigabit speeds.

Potential Causes and Troubleshooting Steps

1. Cable and Connection Verification

2. Cable Quality: Ensure that all Ethernet cables are certified Cat6 or higher. While Cat6 is generally sufficient, faulty or damaged cables can limit speed.

3. Connection Quality: Test each cable individually and confirm that all connectors are properly seated. Use different ports on your switch or router to rule out port issues.

4. Network Adapter Settings

5. Speed & Duplex Settings: Sometimes, the network adapter may default to a lower speed or have incorrect duplex settings. To verify:

   • Open Device Manager.
   • Locate your Ethernet adapter under “Network adapters.”
   • Right-click, select “Properties,” then navigate to the “Advanced” tab.
   • Find the “Speed & Duplex” setting.
   • Ensure it is set to “Auto Negotiation” or explicitly to “1.0 Gbps Full Duplex.”
   • Save changes and restart the network connection.

6. Driver Updates

7. Outdated or incompatible drivers can limit performance. Check the manufacturer’s website for the latest driver updates for your Realtek PCIe GbE Family Controller.

8. Download and install any available updates, then reboot your system.

9. Network Hardware Configuration