Ethernet problem.

Question

Windows 11 Pro. 26H2. Build 26300.9711

Running 5G mobile wi-fi adapter for internet and using ethernet cable for computer. Been using it this way for 3 years when suddenly the ethernet drops out and wi-fi takes over. Have checked the adapter, everything looks good there.

Changed the ethernet cable, but still only have wi-fi available.

Any ideas???

Cheers,

Peter.

Answer 1

Hi,

That’s strange. Let’s try a simple test: shut down your PC completely and unplug it from the power source. Wait about 3 minutes, plug it back in, and turn the PC on. Once it boots up, check to see if the Realtek network driver reappears.

If it doesn’t, we’ll need to take a look at the BIOS to see if the option has been disabled.

Thanks.

Answer 2

Hi,

Could you please provide the "System Summary" from msinfo32.exe? A screenshot would be ideal.

Also, if possible, go to the Start menu > Settings > Network & internet > Advanced network settings > Ethernet, click on the arrow, and check if it is set to "Enabled" and shows a "Link speed."

Thanks

Answer 3

Might have to wait a day or two before I can get the wi-fi adapter tested.

Hope the scraanshot was ok.

Peter

Answer 4

Hi,

Is the network cable showing as connected in your Windows settings?

Search for msinfo32.exe in the search bar, take a screenshot, and post it here so we can see the correct laptop model or desktop configuration.

Thanks

Answer 5

Windows 11 should show whether the Ethernet link itself is detected, so check that status first and then reinstall the Ethernet adapter driver if the wired connection is missing or disconnected.

1. Determine whether Windows detects the wired link

Since replacing the cable did not help:

1. Open Settings → Network & internet.
2. Look for Ethernet and note its status:
   • Ethernet is absent: proceed to Device Manager below.
   • Not connected / cable unplugged: this indicates that Windows is not detecting a physical link. Test the 5G adapter’s Ethernet port with another computer or USB-to-Ethernet adapter, if available. If neither device detects a link, the 5G adapter’s Ethernet port or its Ethernet function is the likely point of failure.
   • Connected, but no internet: skip to the network commands in step 3.

Microsoft recommends testing the same Ethernet connection with another PC to distinguish a computer-side fault from a router/adapter-side fault.^1^

2. Check and reinstall the Ethernet adapter

1. Right-click Start → Device Manager.
2. Expand Network adapters.
3. Locate the wired Ethernet adapter—not the Wi-Fi adapter.
4. Open Properties → General and check Device status.
   • If it is disabled, select Enable device.
   • If it has an error code, record the code.
   • If no Ethernet adapter appears, select View → Show hidden devices and check again.

If the adapter appears but Ethernet remains unavailable:

1. Download the latest Windows 11 LAN/Ethernet driver for the exact PC or motherboard model from its manufacturer, keeping it as a backup.
2. In Device Manager, right-click the Ethernet adapter and select Uninstall device.
3. Select Attempt to remove the driver for this device, then Uninstall.
4. Restart Windows. Windows should reinstall the adapter automatically.
5. If it does not, install the manufacturer driver downloaded in step 1.

Microsoft specifically recommends this driver reinstall when Ethernet stops working, particularly following an update.^1^

3. If Ethernet says “Connected” but has no internet

Open Command Prompt as administrator and run:

netsh winsock reset
netsh int ip reset
ipconfig /release
ipconfig /renew
ipconfig /flushdns

Restart the PC afterward. These commands reset Winsock and TCP/IP, request a new address, and clear the DNS cache.^1^

4. Use Network Reset only as the final software step

Go to:

Settings → Network & internet → Advanced network settings → Network reset → Reset now

This removes and reinstalls all network adapters and returns their settings to defaults. VPN clients, Hyper-V virtual switches, and other networking software might require reconfiguration afterward.^1^

There is currently no officially listed general Ethernet-drop issue for Windows 11 26H2 on the release-health page, and build 26300.9711 is the October 13, 2026 KB5127648 release.^2^^3^ Therefore, rolling Windows back should not be the first action without first identifying whether the Ethernet link, device driver, or 5G adapter’s Ethernet port has failed.

If further diagnosis is needed, provide:

• The Ethernet status shown under Settings → Network & internet
• The exact Ethernet adapter model and any Device Manager error code
• Whether the Ethernet-port link lights illuminate at either end
• Whether another device detects a wired connection from the same 5G adapter port

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References

1. Windows 11
2. Windows 11, version 26H2 known issues and notifications
3. October 13, 2026—KB5127648 (OS Builds 26300.9711, 26200.9711 and 26100. ...