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Capped at 100 mbps for Ethernet Link Speed

DoubleA 5 Reputation points
2025-07-20T06:48:26.1533333+00:00

Hi! I recently built a new PC and I seem to be stuck on 100 mbps while using Ethernet. My current plan is 300 mbps down and up. The link speed is capped at 100 mbps when I go to network settings.

When I'm using wifi on my phone, my speeds are ~300 mbps. I have another PC on the network and it reaches 300 mbps. This means it shouldn't be the router (TP Link Archer C9). I tested the ethernet cable (Cat6) by plugging it into my laptop and the link speed is 1000 mbps, so it shouldn't be the Ethernet cable either.

I turned off the following settings in my network adapter properties:

-Power saving mode

-Gigabit lite

-Green ethernet

I've tried changing the Speed and Duplex setting to both Auto Negotiation and 2.5 gbps, but neither worked.

My set up is:

-Ryzen 7 9800X3D

-Radeon RX 9070XT

-ASUS TUF Gaming B650E-Wifi Motherboard (I uninstalled the Realtek Gaming 2.5GbE Family Controller driver and installed the latest from the ASUS website). I don't think the ethernet port is the issue because I have a very stable 100mbps connection with no stutters at all.

Is there anything else I can do or try? Appreciate any suggestions!

Windows for home | Windows 11 | Internet and connectivity

2 answers

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  1. Pavel Poddubny 1,865 Reputation points Volunteer Moderator
    2025-07-20T07:11:09.0366667+00:00

    Hello,

    1. Open "Run" by pressing Win+R combination, enter here "ncpa.cpl" and press OK
    2. Open your network adapter by double clicking it, Properties -> Configure -> Advanced
    3. See if "EEE Max Support Speed" is set to 1Gbps, and there will be also Gigabit Lite in the list, make sure that it's set to 1Gbps (or higher). You may not have these, but it's important to check. Last thing, there will be always "Speed & Duplex" in the list, so locate this, and set this to 1Gbps full duplex

    Let me know if this works

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  2. franco d'esaro 25,076 Reputation points Volunteer Moderator
    2025-07-20T14:47:54.3633333+00:00

    Hi DoubleA!

    Is the PC's network cable plugged into the LAN wall socket or directly into the router's LAN port?

    Try replacing that network cable with a different brand or higher-quality one, regardless of whether it works on the laptop.

    Are the PC and router in the same room or on different rooms or floors of the house?

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