On top of well-publicized install failures, Microsoft's May 2026 Windows 11 update (KB5089549) is now drawing a second wave of complaints: a smaller group of users say their internet speeds dropped right after the patch installed, and Microsoft has separately confirmed yet another update bug affecting PCs on restricted or firewalled networks. If your home or small-business PC has felt sluggish online since mid-May, the update may be the reason.
What's actually happening
The May 2026 cumulative update for Windows 11, KB5089549, rolled out on May 12-13. Most people install it without trouble, but two distinct problems are now surfacing.
The first is an install failure tied to a full EFI System Partition, which Microsoft has already acknowledged and is mitigating through a server-side rollback. The second — and newer — issue is a noticeable drop in internet speed on a smaller number of Windows 11 machines after KB5089549 installs successfully. Windows Central reports that complaints surfaced shortly after the update went out, mostly on Reddit and Microsoft's own forums, where users describe sharply slower downloads, web browsing, and streaming immediately after installing the patch.
As of this week, Microsoft has not formally documented the networking issue, and the complaints are still scattered rather than confirmed as a widespread bug. Slower internet can be caused by many things — router problems, ISP issues, or background updates — so a single slow speed test isn't proof the update is to blame.
A separate update bug affecting firewalled networks
On top of those two issues, Microsoft this week confirmed a third problem with Windows Update itself. Devices on restricted or air-gapped networks — common at small offices, medical practices, and anywhere with a strict firewall — may see error code 0x80010002 and stop receiving Windows updates from March 2026 onward. Microsoft says the cause is recent changes to download timeout requirements when Windows Update starts a download.
For most home users this won't matter, but if you run a small business with locked-down internet access and your PCs suddenly stopped pulling updates a few months back, this is almost certainly why. The fix requires a Group Policy change and a reboot, which is usually not a DIY job.
How to check if your PC is affected
If your Windows 11 PC has felt slower online since mid-May, do these three quick checks before assuming the update is at fault:
1. Open Settings → Windows Update → Update history and confirm KB5089549 installed on or around May 12-13. If the install failed and rolled back, you'll see it listed with an error.
2. Run a speed test (fast.com or speedtest.net) on the affected PC, then on a phone or another device on the same Wi-Fi. If only the Windows PC is slow, the update is a likely suspect.
3. Restart your network adapter (Settings → Network & internet → Advanced network settings → Network reset) or reinstall your Wi-Fi/Ethernet driver from the manufacturer's site. Microsoft has not pulled the update, so uninstalling it should be a last resort — it also rolls back security fixes for 120+ vulnerabilities patched this month.
If the PC won't boot at all after the update, or you're stuck in a reboot loop, stop and get help before trying recovery steps that could make recovering your files harder.
What This Means for York, PA
If you're in York, Hanover, Dover, or anywhere in York County and your Windows 11 PC has been crawling online or refusing the May update, bring it in to York Computer Repair at 2069 Carlisle Rd — we can confirm whether KB5089549 is the cause and apply the right fix without rolling back your security patches. Walk-ins welcome Mon-Fri 9-5, or call 717-739-9675.
Sources
- Windows 11's May update is causing install failures and slow internet — here's what we know (Windows Central)
- Microsoft confirms patching issues in restricted Windows networks (BleepingComputer)
- Microsoft confirms Windows 11's May 2026 update is failing to install with error 0x800f0922 (Windows Central)