We are experiencing internet performance issues across multiple systems after installing Windows update KB5089549 on Windows 11 version 25H2.

Question

We are experiencing internet performance issues across multiple systems after installing Windows update KB5089549 on Windows 11 version 25H2.

Surya Prakash 40

Issue Details:

Systems experience slow internet connectivity after the update
Web browsing and application access are significantly affected
Multiple users across the organization are impacted
The issue was first observed immediately after deployment of KB5089549

Environment Details:

Operating System: Windows 11 25H2
KB Update: KB5089549

Troubleshooting Performed:

Verified network infrastructure and ISP connectivity; no issues found
Issue appears isolated to Windows systems after the update
Uninstalled the suspected KB update on test systems; however, intermittent slowness still persists
Basic network troubleshooting and system restart procedures were completedWe are experiencing internet performance issues across multiple systems after installing Windows update KB5089549 on Windows 11 version 25H2. Issue Details:
- Systems experience slow internet connectivity after the update
- Web browsing and application access are significantly affected
- Multiple users across the organization are impacted
- The issue was first observed immediately after deployment of KB5089549
Environment Details:
- Operating System: Windows 11 25H2
- KB Update: KB5089549
Troubleshooting Performed:
- Verified network infrastructure and ISP connectivity; no issues found
- Issue appears isolated to Windows systems after the update
- Uninstalled the suspected KB update on test systems; however, intermittent slowness still persists
- Basic network troubleshooting and system restart procedures were completed

Sean Bond 10 Reputation points

2026-05-15T09:29:21.5233333+00:00

I have exactly the same issue. All other devices on the same network are fine apart from the WIndows 11 25H2 device with KB5089549. All was fine before this update.
Formigoni, Houdini 5 Reputation points

2026-05-18T12:29:54.51+00:00

Exactly the same over here!
Gl0wSticks 0 Reputation points

2026-05-19T13:24:06.17+00:00

Both of these fail to install, and ask me to retry. (Tried numerous methods to fix, but I think I am done..)

During installation of these my PC crashed(3 or so days ago) and continues to randomly crash sometimes if I try to install these again. I've spent the last 3-4 days troubleshooting this.. Running SFC, doing all DSIM etc, and various windows operations. MY PC currently runs very slow even though these did not install, my internet is slow, my games run like garbage, and my mouse lags. This completely broke my nvidia drivers, and I had to go into safe mode and do DDU, which the latest nvidia driver installed properly I GUESS, prior it would say installed successfully, but say it's still not.. But now it is. "apparently".

Very tempted to go Linux after this.. First major issue ever encountered though. They better release a hotfix for this tragedy...
Abdullah 5 Reputation points

2026-05-20T01:49:24.9333333+00:00

I have the same issue, it just felt so much slower after the update using browsers and Windows 11 in general. Thought it was related to an Intel Rapid Storage driver that was just updated or a Dell Bios update, all in the same week. Rolled back those drivers but still some issues. Randomly came across a Reddit post about Transparency and Animations; turning them off made things faster for me; faster web loads, new tabs opening, file explorer opening, etc. Not as fast as before update but definitely faster than the recent update lag issue.

Transparency: Settings -> Personalization -> Color -> Turn off Transparency Effects
Animations: Settings -> Accessibility -> Visual Effects -> Turn off Animation Effects

Really trying to avoid a fresh re-install.
Maik 0 Reputation points

2026-05-23T08:09:03.86+00:00

At me, issue only affects Ethernet Connections - WLAN Connection works fine.
Already tried different Network Cards (Intel & RLT), same issue. Mostly UDP seems affected.

Uninstalling KB5089549 didn't help, guess Network Stack have been modified.

Any source where i could check, if theres a fix for that?
Gl0wSticks 0 Reputation points

2026-05-28T09:22:15.23+00:00

They messed up several peoples computer, still no fix after 10+ days is crazy.

Apparently HP computers had conflict with bitlocker blue screen. Which I have an HP desktop, but never encountered any blue screen bitlocker screen that required me to enter a key. I don't even know what the key is even if I had to do it.

I talked with Microsoft chat, and even their QuickAccess application didn't even work. Who is running the company over there, monkey? Fix my PC, demand UPDATE asap. 10+ days of slow PC/Internet/Certain games running like garbage. I've done over 50 hours of troubleshooting their conflict.. I'm tired of it, and I'm not getting paid for solving issues.

RELEASE A FIX.
Rayner Escobar 0 Reputation points

2026-06-11T04:06:13.1233333+00:00

Experiencing same problem, the system seems to connect to the WiFi correctly but does not allow to visit any pages, tried to flush and renew the DNS, rollback update and tried different networks, none seem to work.

3 answers

Your answer

Sean Bond 10 Reputation points

2026-05-15T09:29:21.5233333+00:00

I have exactly the same issue. All other devices on the same network are fine apart from the WIndows 11 25H2 device with KB5089549. All was fine before this update.
Formigoni, Houdini 5 Reputation points

2026-05-18T12:29:54.51+00:00

Exactly the same over here!
Gl0wSticks 0 Reputation points

2026-05-19T13:24:06.17+00:00

Both of these fail to install, and ask me to retry. (Tried numerous methods to fix, but I think I am done..)

During installation of these my PC crashed(3 or so days ago) and continues to randomly crash sometimes if I try to install these again. I've spent the last 3-4 days troubleshooting this.. Running SFC, doing all DSIM etc, and various windows operations. MY PC currently runs very slow even though these did not install, my internet is slow, my games run like garbage, and my mouse lags. This completely broke my nvidia drivers, and I had to go into safe mode and do DDU, which the latest nvidia driver installed properly I GUESS, prior it would say installed successfully, but say it's still not.. But now it is. "apparently".

Very tempted to go Linux after this.. First major issue ever encountered though. They better release a hotfix for this tragedy...
Abdullah 5 Reputation points

2026-05-20T01:49:24.9333333+00:00

I have the same issue, it just felt so much slower after the update using browsers and Windows 11 in general. Thought it was related to an Intel Rapid Storage driver that was just updated or a Dell Bios update, all in the same week. Rolled back those drivers but still some issues. Randomly came across a Reddit post about Transparency and Animations; turning them off made things faster for me; faster web loads, new tabs opening, file explorer opening, etc. Not as fast as before update but definitely faster than the recent update lag issue.

Transparency: Settings -> Personalization -> Color -> Turn off Transparency Effects
Animations: Settings -> Accessibility -> Visual Effects -> Turn off Animation Effects

Really trying to avoid a fresh re-install.
Maik 0 Reputation points

2026-05-23T08:09:03.86+00:00

At me, issue only affects Ethernet Connections - WLAN Connection works fine.
Already tried different Network Cards (Intel & RLT), same issue. Mostly UDP seems affected.

Uninstalling KB5089549 didn't help, guess Network Stack have been modified.

Any source where i could check, if theres a fix for that?
Gl0wSticks 0 Reputation points

2026-05-28T09:22:15.23+00:00

They messed up several peoples computer, still no fix after 10+ days is crazy.

Apparently HP computers had conflict with bitlocker blue screen. Which I have an HP desktop, but never encountered any blue screen bitlocker screen that required me to enter a key. I don't even know what the key is even if I had to do it.

I talked with Microsoft chat, and even their QuickAccess application didn't even work. Who is running the company over there, monkey? Fix my PC, demand UPDATE asap. 10+ days of slow PC/Internet/Certain games running like garbage. I've done over 50 hours of troubleshooting their conflict.. I'm tired of it, and I'm not getting paid for solving issues.

RELEASE A FIX.
Rayner Escobar 0 Reputation points

2026-06-11T04:06:13.1233333+00:00

Experiencing same problem, the system seems to connect to the WiFi correctly but does not allow to visit any pages, tried to flush and renew the DNS, rollback update and tried different networks, none seem to work.

Answer 1

Jason Nguyen Tran 19,865 Independent Advisor

Hi Surya Prakash,

Based on your description, the slowdown appears tied to changes introduced by the update rather than your network infrastructure. Some cumulative updates can affect network stack components, including NIC drivers or TCP/IP optimizations. Even after uninstalling the update, residual configuration changes may persist, which explains why intermittent slowness continues.

The first step I recommend is to confirm that all affected systems have the latest NIC drivers from the hardware vendor, not just the default Windows drivers. Next, check whether the update modified advanced adapter settings such as offloading, RSS, or MTU size. Resetting these to defaults often restores performance. Running “netsh int ip reset” and “netsh winsock reset” can also clear any lingering stack changes.

If the issue persists, you may want to temporarily pause updates on production systems until Microsoft releases a servicing fix. In parallel, monitor the Windows Update Health Dashboard for advisories related to KB5089549, as Microsoft typically publishes known issues and workarounds there.

For enterprise environments, another best practice is to validate cumulative updates in a pilot group before broad deployment. This helps catch regressions like the one you’re experiencing.

I hope this explanation helps clarify the situation. If this answer is helpful, please don’t forget to hit “Accept Answer”.

Jason.

Surya Prakash 40 Reputation points

2026-05-14T04:14:46.1266667+00:00

I have tried the recommended troubleshooting steps, including updating the NIC drivers, resetting the TCP/IP and Winsock stack, and verifying the adapter advanced settings. I also uninstalled the suspected KB update and tested after reboot, but the issue still persists intermittently.

Additionally, I performed a system restore on my machine to revert to an earlier state, however the slowness issue is still present even after the restore. At this point, the behavior appears to be consistently related to the recent Windows update changes affecting multiple systems.
Gl0wSticks 0 Reputation points

2026-05-19T14:00:13.33+00:00

Microsoft just needs to fix it. They borked many peoples pc.

I never sign into this website, but I had to post.
Jason Nguyen Tran 19,865 Reputation points Independent Advisor

2026-05-20T04:15:33.5433333+00:00

Hello,

At this point, the behavior you’re describing does appear to be tied to recent changes introduced by KB5089549 and how it interacts with the Windows 11 25H2 network stack. Since you’ve ruled out infrastructure and ISP issues, the focus should remain on system-level components.

I recommend confirming that all affected systems are running the very latest NIC drivers directly from the hardware vendor (Intel, Realtek, Broadcom, etc.), not just those provided through Windows Update. It’s also worth resetting advanced adapter features like RSS, offloading, and MTU size back to defaults, as these can be impacted by update changes. In some cases, disabling hardware offload temporarily has improved performance.

Additionally, keep an eye on the Windows Update Health Dashboard, as Microsoft will publish advisories and hotfixes for KB5089549 if widespread issues are confirmed. In the meantime, you may want to pause further rollout of this update across your environment until a fix is available. Validating cumulative updates in a small pilot group before broad deployment can help avoid these kinds of disruptions.

I know this has been a time-consuming issue, but your testing has already narrowed down the root cause significantly. Once Microsoft releases a servicing update, the performance problems should stabilize.

Jason.

Answer 2

No internet performance or connectivity issues related to Windows 11, version 25H2 or to KB5089549 are described in the provided context. The context only lists other known and resolved issues (for example, HTTP.sys/IIS connection resets, Direct Access reconnection issues, app hangs when saving to cloud storage, Microsoft account sign-in failures, specific KB install failures, and app-specific problems), and none match organization-wide slow internet performance after KB5089549.

Because of this, no KB-specific workaround or fix for KB5089549 can be provided from the context. The only supported guidance in similar Windows update issues in the context is:

Ensure the latest cumulative/security updates are installed when Microsoft has released a fix for a known issue.
If an update is suspected of causing issues and uninstalling it does not fully resolve the problem, perform an in-place repair/reinstall of Windows 11 using installation media, as was done to resolve repeated update failures and post-update app corruption in similar cases.
If the problem persists across multiple systems and is not covered by documented known issues, open a support case with Microsoft so the issue can be investigated and, if needed, addressed in a future update.

References:

Answer 3

Cristian Gavrilut 0

I had to uninstall the updates from May as they were causing any streaming service includding youtube but not limited to it to not be able to load any videos. Internet download speed I have is 800 MB/s and uploads 100Mb/s videos were like continuously loading regardless of browser. After uninstalling updates my system works again. System hardware: RTX 4090, AMD Ryzen 9 7950X3D, 64bGB RAM. Edition Windows 11 Pro, current version: 24H2. I spent hours troubleshooting and trying everything until I decided to uninstall windows updates from May includding the above.

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We are experiencing internet performance issues across multiple systems after installing Windows update KB5089549 on Windows 11 version 25H2.

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