Windows 11 KB5089573 Update Slow Internet Fix

Windows 11 KB5089573 Update Errors and Slow Internet Fix

Direct Answer: The KB5089573 update for Windows 11 is causing two main problems: the update itself may fail to install with error codes 0x800f081f and 0x80073701, and even after a successful install, some users are reporting significantly slower internet speeds. I have seen both issues across multiple machines this month. I have been troubleshooting this on several machines, and the fix depends on which problem you are hitting. If the update fails to install, you need to clear the update cache and manually download the standalone package. If the internet is slow after installing, you likely need to reset your network stack or uninstall the update entirely.

What KB5089573 Is Supposed to Do

Microsoft released KB5089573 as a cumulative update for Windows 11 in late May 2026. The official changelog mentions performance improvements for File Explorer, fixes for a memory leak in the Widgets panel, and security patches for several networking components. On paper, it looks like a routine monthly update.

The problem is that this specific update touches the Windows networking subsystem in ways earlier updates did not. Its TCP/IP and DNS resolver patches cause regressions on certain hardware — Realtek adapters and older Wi-Fi drivers especially.

How to Check If KB5089573 Is Already Installed

Before you start troubleshooting, confirm whether the update is on your system at all. Open Settings > Windows Update > Update history. Look for KB5089573 in the list of recently installed updates. If you see it listed alongside a failed status, that explains the error codes.

You can also check using PowerShell. Open it as administrator and run Get-HotFix -Id KB5089573. Details returned means it is installed. An error saying “not found” means the install failed — a different fix is needed.

This step is important because the fix is different for each scenario. A failed install needs component store repair. A successful install with slow internet needs network stack changes. Mixing up the two wastes hours.

When the KB5089573 Install Fails

If you are sitting at 99% stuck on the download or getting an error during installation, you are not alone. The most common failure scenarios I have seen are:

• Error 0x800f081f: Windows could not find the source files needed for the update. This usually means the update component store is corrupted.
• Error 0x80073701: One or more update components are missing or damaged. This is similar to 0x800f081f but specific to the servicing stack.
• Download stuck at 99%: The update downloads fully but cannot verify the integrity of the downloaded files. A corrupt download cache is usually the culprit.
• Reboot loop after install: The update partially installs but fails during configuration, causing Windows to roll back and try again on the next boot.

These failures are more common on systems that have not received a quality update in 3-6 months. The Windows Update component store decays over time, and a large cumulative update like KB5089573 can expose that decay. Systems updated regularly rarely hit these errors.

How to Fix KB5089573 Install Failures

I have tested these steps on four different Windows 11 machines that failed to install KB5089573. The success rate was three out of four. The fourth needed a full uninstall and block. Try them in order — skip ahead if a step clearly does not apply to your situation.

Step 1: Clear the Windows Update Cache

Press Win + R, type services.msc, and press Enter. Find Windows Update, right-click it, and select Stop. Keep the Services window open.

Now open File Explorer and go to C:\Windows\SoftwareDistribution\Download. Delete everything inside. Administrator permission is required — click Continue.

Go back to Services. Right-click Windows Update and select Start. Try checking for updates again in Settings > Windows Update.

Step 2: Run the Windows Update Troubleshooter

This sounds basic, but the built-in troubleshooter handles component store corruption better in Windows 11 than it did in Windows 10.

Go to Settings > System > Troubleshoot > Other troubleshooters. Find Windows Update and click Run. Follow the prompts. If it finds and fixes corruption, restart and try the update again.

Step 3: Use DISM to Repair the Component Store

Still stuck? The component store needs a deeper fix. Open Command Prompt as administrator — search for “cmd” in the Start menu, right-click, and select Run as administrator.

Run this command:

DISM /Online /Cleanup-Image /RestoreHealth

This scans the Windows image and repairs corruption by pulling replacement files from Windows Update. Expect it to run 15-30 minutes. Do not close the window.

When that finishes, run:

sfc /scannow

SFC checks system files for integrity violations. It takes about 10 minutes. Restart the PC afterward.

Step 4: Manually Download and Install KB5089573

If Windows Update still fails, bypass it entirely. Go to the Microsoft Update Catalog and search for KB5089573. Find the package that matches your system architecture (x64 for almost all modern PCs).

Download the standalone .msu package. Double-click to install. This bypasses the Windows Update client entirely and often works when the built-in updater fails.

Step 5: Use the Windows 11 Installation Assistant

If the standalone installer also fails, use the Windows 11 Installation Assistant from Microsoft’s official download page. This tool performs an in-place upgrade that installs the latest cumulative update as part of a full OS refresh. It takes longer but has the highest success rate.

When Internet Slows Down After KB5089573

This is harder to diagnose and more frustrating. The update installs fine, but suddenly pages load slowly, downloads crawl, and video calls stutter. The culprit is likely one of the TCP/IP security patches. On certain drivers, the new window scaling behavior creates packet loss.

The key symptom: a speed test looks normal, but actual browsing and downloads crawl. That signals a TCP window scaling or DNS problem, not a bandwidth issue.

How to Fix Slow Internet After KB5089573

Step 1: Run the Network Troubleshooter

Head to Settings > System > Troubleshoot > Other troubleshooters. Find Network and Internet and click Run. This resets the adapter and clears the DNS cache — all automatic.

Step 2: Reset the Network Stack Manually

If the troubleshooter does not cut it, open Command Prompt as administrator. Run these five commands in order:

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

Reboot afterward. This resets the TCP/IP stack and DNS resolver — exactly the components KB5089573 changes.

Step 3: Disable TCP Auto-Tuning

TCP auto-tuning adjusts the receive window dynamically. KB5089573 sets this scaling too aggressively on certain adapters.

Open Command Prompt as administrator and run:

netsh int tcp set global autotuninglevel=disabled

Restart the PC. If the internet speeds return to normal, the update was setting an incorrect TCP window scale. You can leave auto-tuning disabled, or you can set it to “normal” instead of “disabled” with:

netsh int tcp set global autotuninglevel=normal

Step 4: Update Your Network Adapter Driver

Driver versions matter here. The KB5089573 networking changes hit Realtek and Intel adapters the hardest. If updating makes things worse, roll back the driver in Device Manager under Properties > Driver > Roll Back Driver.

Open Device Manager from the Start Menu. Expand Network adapters. Right-click your Wi-Fi or Ethernet adapter and select Update driver > Search automatically for drivers.

If Windows does not find a newer driver, go to your PC manufacturer’s website (Dell, HP, Lenovo, ASUS) or the adapter manufacturer’s website directly and download the latest driver manually.

Step 5: Uninstall KB5089573 as a Last Resort

Still having problems? Remove the update and block it.

Go to Settings > Windows Update > Update history > Uninstall updates. Find KB5089573, select it, and click Uninstall. Restart the PC.

To block reinstallation, download the Show or Hide Updates Troubleshooter from Microsoft. Run it. Select Hide updates and choose KB5089573. Windows will skip it from now on.

What to Do If You Need to Block the Update Entirely

If you manage multiple PCs or just want to avoid this headache entirely, you can pause updates temporarily or defer them.

Pause updates for up to 5 weeks: Go to Settings > Windows Update and click Pause for 1 week. You can extend this up to 5 weeks.

Use Group Policy to defer updates (Windows 11 Pro only): Press Win + R, type gpedit.msc, and navigate to Computer Configuration > Administrative Templates > Windows Components > Windows Update > Manage updates offered from Windows Update. Enable the policy Select the target Feature Update version and enter “Windows 11” with version “23H2” or “24H2” depending on what you are currently running.

Use the Registry to block a specific update (Windows 11 Home): Open Registry Editor as administrator. Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate. Create a new DWORD (32-bit) value called ExcludeWUDriversInQualityUpdate and set it to 1. This prevents driver-related updates included in KB5089573 from installing.

Check back in 2-4 weeks for a fixed version. Microsoft typically releases an out-of-band update to fix regressions like this within a month. Unhide the update using the Show or Hide Updates Troubleshooter once the fixed version is available. You can check the Windows Update forum on Microsoft Answers for confirmation that the issue is resolved before unhiding.

Decision Summary

• If KB5089573 fails to install → Clear the SoftwareDistribution cache, run DISM, then try the standalone package from the Microsoft Update Catalog.
• If the update installs but internet is slow → Reset the network stack with netsh commands first. If that does not work, disable TCP auto-tuning. If still slow, uninstall the update.
• If you manage multiple PCs → Pause updates for 5 weeks and monitor the Microsoft forums for a fixed version of KB5089573.
• If you are on a Realtek network adapter → Update your network driver before or immediately after installing KB5089573. This combination causes most of the internet slowdown reports.
• If you need to avoid this update entirely → Use the Show or Hide Updates tool to block it permanently.

Frequently Asked Questions

Q: Is KB5089573 a security update or a feature update? A: It is a cumulative security update that also includes non-security improvements. Microsoft releases these on the second Tuesday of each month (Patch Tuesday). KB5089573 is the June 2026 cumulative update for Windows 11.

Q: Will uninstalling KB5089573 make my PC insecure? A: Yes, in theory. It removes the security patches included in the update, some of which address actively exploited vulnerabilities. Microsoft usually fixes regression issues like this internet slowdown within 2-4 weeks. I recommend checking for a new cumulative update every week until the fixed version is released.

Q: Can I install KB5089573 manually without Windows Update? A: Yes. Download the standalone package from the Microsoft Update Catalog. Search for KB5089573 and select the version that matches your system architecture (x64 for most users). Double-click the downloaded .msu file to install.

Q: Does KB5089573 affect Windows 10 as well? A: No, this is Windows 11 only (versions 22H2, 23H2, and 24H2). Windows 10 gets a different cumulative update each month with its own KB number. The networking regression here is Windows 11-specific so far.

Q: Will resetting my PC fix the KB5089573 issues? A: It would, because a reset removes the update entirely and starts fresh. But that is an extreme step for what is likely a temporary driver compatibility issue. Try the network stack reset and driver update first. Only consider a full reset if the slowdown is intolerable and you have already spent hours troubleshooting.

Further Reading

Want to go deeper? Check out these related guides:

• Will Reinstalling Windows Fix Blue Screen Errors? — Blue screen errors are frustrating. Reinstalling Windows fixes software-related crashes but will not help with hardware issues.
• Does Resetting Windows Remove Viruses Completely? — Yes, resetting Windows removes most common viruses and malware.
• Speed Up Your Slow PC in 2026 — Ten essential Windows performance tweaks for a faster PC without reinstalling.