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Internet speed seems limited to 100 Mbps on Windows 11

Gaz 0 Reputation points
2026-05-14T21:00:45.3666667+00:00

I am running Windows 11 on a PC with a 1 gigabyte capable network adapter - Realtek PCIe GbE Family Controller.

We are on 1 Gb/s internet speed.

The router is a Nokia Beacon 3.1. It reports that this PC has a Rx and Tx of 1000 Mb/s.

Win 11 is set to 1 Gb/s in the controller's simplex / duplex settings.

Running speed test I get download speeds of about 100 Mb/s and upload speeds of up to 300 Mb/s.

What in Windows 11 is throttling the download speeds?

Windows for home | Windows 11 | Internet and connectivity
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  1. Jobelle ann Candelaria 495 Reputation points Independent Advisor
    2026-05-14T22:16:05.7966667+00:00

    Hi Gaz,

    Thanks for posting your question here. I would like to kindly inform you that this issue is not caused by Windows 11 throttling your speed, instead this is due to reduced network, mainly caused by both of Ethernet cable quality and network adapter behavior (Realtek driver/settings).

    You may need to check and replace the Ethernet cable, you can use Cat5e or Cat6 (Avoid damaged or low-quality cables). Also, you can try to try a different router port, plug into another LAN port on the router.

    Please follow these as the next steps:

    1. Verify adapter settings: Go to Device Manager, select Network Adapter, then Properties and select Advanced:
    • Set Speed & Duplex to Auto Negotiation
    • Disable: Energy Efficient Ethernet (EEE) and Green Ethernet
    1. Update or reinstall the network driver
    • Install the latest driver from the motherboard or Realtek website
    • Alternatively, reinstall the driver via Device Manager
    1. Reset the network stack. Run Command Prompt as Administrator:

    netsh int ip reset

    netsh winsock reset

    ipconfig /flushdns

    Restart your PC afterward.

    Let me know if you have questions, I am here to help.

    Give back to the Community. Help the next person who has this issue by indicating if this reply solved your problem. Click Yes or No below.

    Thanks,

    Jobelle C.

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