Slow wifi after updating to Windows' Creator's Update

Question

Immediately after installing the Windows 10 version 1703 Creator's Update (CU), wifi speeds are very slow. Checking the speed on speedtest I was getting 2-7 Mbps download when I normally get 50-80 Mbps. Searching shows many with the same issue after updating to CU, but few if any solid answers.

Checking another Windows 10 machine without CU gave normal internet speeds so I ruled out the router or any temporary internet speed issue.

I'm using the following USB wifi adapter:

TP-LINK Archer T4U (version 2.0)

I tried downloading the latest driver from TP-LINK and installing but windows just says "The best driver software is already installed".

Answer 1

I was ready to buy a new adapter but since many in the same class have the same chipset, Realtek RTL8812AU, I figured it might be likely that they would have the same issue so I decided to try hard to fix it.

Here's how I fixed it:

1. First download the http://www.tp-link.com/us/download/Archer-T4U.html#Driver This gave me: ArcherT4U(US)_V2_161129_Windows.zip with a "Windows 10 64bit" folder inside. This step is important, you don't want to be stuck without internet and have no driver.

2. Windows Key + x go to "Apps and Features", find the tp-link driver and utility and uninstall. I rebooted.

NOTE: A little scarily, after doing this I could not get the adapter to work. Going to device manager and right clicking on Network Adapters and choosing Scan for hardware changes would show the adapter with the yellow exclamation and right clicking and choosing Update driver and letting windows search OR browsing for files and saying search for drivers in this location would not work. The device is supposed to be plug n play on windows 10 but removing and re-inserting the adapter, uninstalling from device manager, and disabling/re-enabling would not get windows to "plug n play". In contrast when I first got it, it worked out of the box.

3. The key was right clicking on the device in the Device Manager, choosing Update driver, choosing Browse my computer for driver software, Let me pick from a list of available drivers on my computer, Have Disk, browsed to my ArcherT4U(US)_V2_161129_Windows folder I download earlier and chose the "Windows 10 64bit" folder and hit ok.

After doing this I had connectivity again and my speeds were back to normal!

The below article gave me the idea to uninstall the driver and reinstall because of possible corruption. Microsoft rep mentioned:

There are chances that some driver files are getting corrupted when updating our system

https://answers.microsoft.com/en-us/windows/forum/windows_10-networking/windows-10-creators-update-wifi-very-slow-problem/ff4c9f4a-f7f8-443a-932c-30603066e925

Answer 2

I had the same problem with my TP-Link Archer T4UH adapter after the Windows 10 Creator's Update. As mentioned, the RTL8812AU chipset seems to be the culprit. The newer driver that windows automatically installs is functional but very slow with download speeds. Some online research shows folks having success when they get windows to recognize an earlier version of the driver. Like the above post I went to the manufacturers support webpapge and downloaded their latest version of the driver. Theirs was dated Dec. 2015 as opposed to the windows Oct. 2016. Within the driver ZIP file was a setup utility. Running the setup utility overwrote the windows driver. (Trying to update driver through windows directly just kept giving me the "you already have the latest driver" window). I now have my fast internet back! I'll just have to make sure windows doesn't try and update it on its own.