Internet speed has dropped greatly

Question

Internet speed has dropped greatly

JanDinSC 0

Since installing the latest Windows Update (5/26/2026), our Internet speed dropped from 940 mbps to 440 mbps via Ethernet connection. Could something within this update be causing this issue, and if so, any suggestions on a fix?

Thank you in advance for any assistance you might give.

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2 answers

Your answer

Answer 1

John DeV 168.7K Independent Advisor

Hi, good day!

I'll be asking a few questions so I can have a better idea what solutions to provide.

What specific update did you install recently?

Can you take a screenshot of your Update history and post it in your next reply?

Have you tried the solutions suggested by the AI?

Note: Don't include any personal information or sensitive data as Microsoft Q&A is a public forum.

I look forward to receiving your update and I'm willing to collaborate with you till we resolve the issue. Do keep me informed by clicking "Add comment" below instead of Yes or No button.

Diane Harley Brown 0 Reputation points

2026-05-30T16:37:38.88+00:00

when I go to different sites it takes a very, very long time to download. Sometimes it takes over an hour to download. I spoke with Dell, the computer company. I also spoke with my Internet company and Xfinity my WiFi company. After they checked everything, each one of them said, that it was a Microsoft issue and I needed to contact Microsoft.
JanDinSC 0 Reputation points

2026-05-30T18:03:06.4533333+00:00

We are checking out the AI answer to this issue right now. If that does not seem to solve the issue, we will get to you. If that is alright with you? Thank you.
John DeV 168.7K Reputation points Independent Advisor

2026-05-30T22:42:01.44+00:00

That sounds good, thank you for the update. Please let me know how it goes.

Answer 2

Yes, a recent Windows update can affect effective Ethernet throughput, typically via driver or network stack changes, even when the line itself is still healthy. Use a structured approach to isolate whether the issue is Windows, the adapter/driver, or the router/ISP.

Verify the physical/network side

Confirm the Ethernet cable is fully seated at both the router and PC, and that it is the same cable and router port used before the update.
Try a different Ethernet cable and a different router port. If the alternate cable/port restores full speed, the original cable/port is at fault, not Windows.
If possible, run a speed test from another device on the same router (preferably another PC via Ethernet). If that device still gets ~940 Mbps, the issue is specific to the updated PC.

Check Ethernet status in Windows

Open Settings > Network & internet.
Select Ethernet and confirm it shows Connected and that the link speed reported by Windows (if shown by the adapter) is 1.0 Gbps. If it shows 100 Mbps or similar, the link is negotiating at a lower speed due to cable/port/driver issues.

Run the built-in network troubleshooter

On Windows 11, open Settings > Network & internet.
Scroll to Network troubleshooter and run it. Follow the prompts and apply any suggested fixes.

Reinstall the Ethernet adapter driver Updates can sometimes leave the NIC driver in a bad state. Reinstalling forces Windows to reload a clean driver.

Before uninstalling, if possible, download the latest Ethernet/LAN driver from the PC or motherboard manufacturer and save it locally.
Select Search on the taskbar, type Device Manager, and open it.
Expand Network adapters and locate the Ethernet adapter.
Right‑click it and select Uninstall device.
Check Attempt to remove the driver for this device if available, then select Uninstall.
Restart the PC (Start > Power > Restart).
After restart, Windows will reinstall the adapter automatically. If it does not, install the manufacturer driver downloaded earlier.
Test speed again.

Use Network Reset as a last resort If the problem started immediately after the update and persists after driver reinstall, reset the entire network stack.

Go to Settings > Network & internet.
On Windows 11: select Advanced network settings > Network reset.
Select Reset now and confirm.
The PC will restart; afterwards, reconfigure any VPN clients or virtual switches as needed.
Test Ethernet speed again.

Compare with Wi‑Fi and other services

Run the same speed test over Wi‑Fi on the same PC. If Wi‑Fi still reaches expected speeds while Ethernet is capped, this further confirms an Ethernet‑specific driver/negotiation issue.
If all devices and both Wi‑Fi and Ethernet now top out around 440 Mbps, the bottleneck may be on the router/ISP side coincidentally with the update; contact the ISP and verify provisioned speed.

If none of the above restores previous throughput and other devices still achieve ~940 Mbps on the same router, roll‑back of the specific NIC driver (via Device Manager > adapter > Properties > Driver > Roll Back Driver) or contacting the PC/motherboard vendor for an updated Windows 11–compatible driver would be the next step.

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