Windows 11 1. Slow Data Transfer using Windows Explorer with Windows 11

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I upgraded from Windows 10 Pro to Windows 11 Pro on Dell XPS 8940 purchased 2 years ago. I upgraded a few months ago when Windows Update said my computer was ready. The upgrade went smoothly with no issues.

I have a Network Attached Storage (NAS) unit attached through my router with gigabit Ethernet (using CAT 6 cables). I also have an external 4TB hard disk in a USB 3 enclosure that is usually not connected. Once a month, I do a complete backup of the computer to the NAS, and then I attach the external USB 3 drive to my computer with a USB 3 cable and copy the backup files from the NAS to the external drive. The total amount of data copied is about 150 GB in several files that are each about 28GB. I do this by using Windows Explorer to copy the files from a mapped drive on the NAS to the drive letter of the eternal drive.

When I was using Windows 10, the transfer speed of this copy operation was about 100 MB/sec (as reported by Windows Explorer). Since updating to Windows 11 (and using exactly the same hardware), the max transfer speed is about 70 MB/sec. I have checked the setting for write caching on the USB drive and turning it on or off does not make any difference. What could be causing this?
 
Microsoft limits network bandwidth by up to 80% to accommodate system activity. When you transfer large files, this limit may kick in and limit your network performance, resulting in Windows file transfer slowing down. That being said you can use Group Policy to limit or even remove it.

Windows Key + R type gpedit.msc Travers to Computer Configuration \ Administrative Templates \ click on Network and double click doubleQoS Packet Scheduler in the right pan. double-click Limit Reservable Bandwidth In the box that comes up Click Enabled, then you can adjust the default Bandwidth limit 80% value to a smaller percentage or even to zero.

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Microsoft limits network bandwidth by up to 80% to accommodate system activity. When you transfer large files, this limit may kick in and limit your network performance, resulting in Windows file transfer slowing down. That being said you can use Group Policy to limit or even remove it.

Windows Key + R type gpedit.msc Travers to Computer Configuration \ Administrative Templates \ click on Network and double click doubleQoS Packet Scheduler in the right pan. double-click Limit Reservable Bandwidth In the box that comes up Click Enabled, then you can adjust the default Bandwidth limit 80% value to a smaller percentage or even to zero.

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I tried to reply earlier but it seems not to have posted.

Thank you for your interest. I tried your suggestion and it did not work. Then I tried somethings that I should have tried before doing the original post. I copied from the NAS to a spare internal hard drive, and it copied at the original (Windows 10) speed of about 100 MB/sec! From this I concluded that the network was not the problem and it had to be somewhere in the USB chain. I tried a different external USB drive, and again got 100 MB/sec. So, it was an issue with the USB drive. Here is what fixed the problem. Under Windows 10, I had assigned a drive letter to the drive with the Disk Management applet. So with Windows 11, I used Disk Management and removed the assigned drive letter from the drive. I rebooted, used Disk Management to reassign the drive letter to the drive, and tried the copy operation again. Presto! I got 100 MB/sec. So, in some way when upgrading Windows 10 to Windows 11, it loses some information regarding disks that have assigned drive letters.

Thank you very much for your help.
 
Good job solving your issue at hand. Also, you may want to think about picking up a 4-Port USB 3.1 PCIe Card - 10Gbps - 3x USB with 2x Dedicated Channels If you are serious about picking up transfer rates. I think this will help. Keep in mind the link I posted is just an example. There are many cards out there. So if you decide to do this, make sure you pick up a card with "Dedicated Channels" So you can utilize the best transfer rates "That Is Important" If you do this I would love to see the results. One more link. This will give you many options whether your MB can handle them or not. Love to see your specs. Network Adapter Cards
 
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