Surface Pro 4 or Surface Book with a slow WiFi connection? Here is a simple fix

For those running a new Surface Pro 4 or Surface Book there is a very small subset of you with unique Wi-Fi access points that may be getting slow connections despite high-speed access.

Some users are reporting that their connection starts with high throughput but quickly dwindles down to a crawl. Microsoft support has confirmed a small driver setting that is causing this issue in their support forums.

"We have a known issue with .41 that results in low throughput with specific access points. The issue is specific to MAC layer aggregation (AMSDU over AMPDU) and only impacts a small subset of access points. We are working on a fix for an upcoming update. Until the fix is available, please update the registry key setting to work around this issue."

One example of this was from someone using a Comcast router, another with a Netgear Nighthawk X8 router and some general issues with 5 GHz connections. Luckily, there is an easy fix:

  1. Press Windows button. Search for Regedit. Open it
  2. Navigate to the following path: HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\mrvlpcie8897
  3. Find the item labeled "TXAMSDU." Double tap and modify the value from 1 to 0
  4. Restart the machine

We have not experienced these connection issues on any of our Surfaces, and it does not appear to be widespread either due to the specific nature of the MAC layer in question. Still, if you are experiencing a slow Wi-Fi connection despite having high speed access it may be worth taking the 30 seconds to enable this registry change. If you are not experiencing these connection problems changing the registry will likely have little impact on your current setup.

Source: Microsoft Answers; via Windows Central Forums

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Daniel Rubino

Daniel Rubino is the Editor-in-chief of Windows Central. He is also the head reviewer, podcast co-host, and analyst. He has been covering Microsoft since 2007, when this site was called WMExperts (and later Windows Phone Central). His interests include Windows, laptops, next-gen computing, and watches. He has been reviewing laptops since 2015 and is particularly fond of 2-in-1 convertibles, ARM processors, new form factors, and thin-and-light PCs. Before all this tech stuff, he worked on a Ph.D. in linguistics, watched people sleep (for medical purposes!), and ran the projectors at movie theaters because it was fun.