Fix Windows Update Pulling KB Files From a Slow Source on Windows 11

Quick fix: Open Settings → Windows Update → Advanced options → Delivery Optimization and turn Allow downloads from other PCs on, choose PCs on my local network and PCs on the Internet, and set a download cap that prefers peers over the slow Microsoft CDN. For totally hung downloads, run BitsAdmin /reset /allusers and let Windows Update pick a new endpoint.

Windows Update has been downloading the same 800 MB cumulative update for an hour. The progress bar inches forward. Your Internet is fast and other downloads work normally. Something has Windows pinned to a slow Microsoft CDN node, or to a peer that’s no faster than dial-up. The fix is to either redirect to faster sources or to reset the download queue entirely.

What causes slow KB downloads

Windows Update uses Delivery Optimization (DO) as its download client. DO splits each KB into pieces and pulls them from multiple sources: the Microsoft CDN, other Windows PCs on your network, and other Windows PCs on the Internet. The mix depends on your DO settings. The slow case usually happens when DO is set to LAN-only, finds no peers on your network, and falls back to a CDN node that’s saturated — or worse, when DO picks an Internet peer with poor upload bandwidth and downloads at peer-upload speed.

The other slow case is when the Background Intelligent Transfer Service (BITS) has a corrupted queue and re-retries the same failed chunk endlessly. That requires a reset, not a configuration change.

Method 1: Allow Delivery Optimization to use Internet peers

1. Open Settings → Windows Update → Advanced options → Delivery Optimization.
2. Toggle Allow downloads from other PCs on.
3. Choose PCs on my local network and PCs on the Internet.
4. Scroll to Advanced options. Under Download settings, set Absolute bandwidth for foreground downloads to a high value (your Internet’s rated speed or higher). Don’t leave the “percentage of measured bandwidth” option — on metered connections it can throttle to near-zero.
5. Save and return to Windows Update. Click Resume updates if available, or click Check for updates to force a fresh attempt.

The mixed-source DO mode usually finds at least one fast peer and the download finishes quickly. If your network blocks peer-to-peer traffic, this won’t help — move to Method 2.

Method 2: Reset the BITS download queue

Stuck BITS jobs survive reboots. Wiping them forces Windows Update to start fresh.

1. Open an elevated Command Prompt.
2. Run:
   
   net stop bits

net stop wuauserv

net stop dosvc

bitsadmin /reset /allusers

del “%ALLUSERSPROFILE%\Application Data\Microsoft\Network\Downloader\qmgr*.dat” (legacy path; OK if the file isn’t there)
   
   net start dosvc

net start wuauserv

net start bits
3. Return to Windows Update and click Check for updates. The KB download starts from zero, often at full Internet speed.

This is the standard fix for “Windows Update is stuck.” The reset clears any corrupted queue entries and lets the service negotiate a fresh CDN node.

Method 3: Force a specific CDN endpoint

If you suspect the CDN node you’re hitting is slow regionally (more common on cellular and satellite connections), you can hint at a different one via DNS.

1. Open Settings → Network & internet → Wi-Fi (or Ethernet), click your network, and set DNS to Manual.
2. Use Cloudflare (1.1.1.1 / 1.0.0.1) or Google (8.8.8.8 / 8.8.4.4) as the resolver. Different resolvers return different CDN endpoints for Microsoft’s GeoDNS.
3. Run ipconfig /flushdns in an elevated terminal.
4. Open Windows Update and retry the download.

This is a niche fix but it occasionally produces dramatic speedups on connections where the default ISP DNS is routing you to a slow Microsoft edge.

How to verify the fix worked

• Windows Update download speed matches your Internet’s rated download (a 100 Mbps connection should pull KB files at ~10 MB/s).
• Open Task Manager, go to the Performance tab, click Ethernet or Wi-Fi. Download rate during update matches your speed.
• Run Get-DeliveryOptimizationStatus | Select-Object FileSize, BytesFromPeers, BytesFromHttp. The breakdown shows DO is pulling from both sources.

If none of these work

If updates remain slow after both DO config and a BITS reset, check whether a third-party antivirus is scanning every chunk (some AV products do this and can throttle to a few hundred KB/s) — temporarily disable AV and retest. For corporate networks, ask IT about WSUS or Configuration Manager — you may be pinned to an on-premises server that’s slow or unreachable. For metered connections, Windows defers updates and downloads at minimum priority; turn off the metered toggle on your network properties if you want full-speed updates.

Bottom line: Slow KB downloads are either a DO source mix problem or a corrupted BITS queue. Method 1 expands the source list; Method 2 wipes the queue. One of those two fixes nearly every “stuck Windows Update” case.