Windows 11 PRO 22H2 Slow SMB Download

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Did you find a solution to this problem? I have the same issue. Same switch running windows 11 pro vs 10 is giving me roughly 50% of the expected speed from NAS to windows machine.

As stated above this is only showing up on windows 11 pro. To test I had a clean install back-to-back.

Thanks for info. Unfortunately I have no solution but have a lot of evidences the SMB protocol does not work correctly on Windows 11 PRO 22H2. So, I sent the ticket to NAS Support Team and second ticket to Windows Support Team to investigate the SMB issue.

I had online meetings with Windows Support Team, they checked my Windows settings (especially network settings) and verdict is... we do not know now. The agreement is they will try to investigate the SMB issue offline. So I have to wait for Windows Support response.

However, I did tons of different test in my environment and my conclusions are as follow:

1.

Windows 11 PRO 22H2 does not inform about need of NIC driver update, what's more, Windows suggested that my current NICs drivers are up-to-date. However, it wasn't true, so I manually updated PC NICs drivers. The update resolved one issue connected to test results reported by tools like e.g. CrystalDisk. Now, this tool reports READ 570-590MB/s and WRITE 570-580MB/s in multichannel SMB env. 2x2.5Gbps. So I am closer to the proper solution BUT unfortunately it does not resolve all SMB problems (below explanation).

2.

Because of success described in point 1, I prepared 10GB file to transfer it using Windows File Explorer and Windows Commander. The test failed and results disappointed me. The same SMB issue again, the downloading transfer speed is about 200 MB/s vs uploading speed about 550 MB/s. No improvement at all. My NAS network monitor shows bizarre numbers in terms of downloading speed in SMB multichannel environment, NAS NIC LAN1 download speed is 100 MB/s vs upload speed about 300 MB/s, the same bizarre numbers in NAS NIC LAN2. It means the total LAN1+LAN2 download speed is 200 MB/s vs almost 600 MB/s of upload speed.

3.

Because of fail in point 2, I had to check my hardware (PC, NICs, NAS). I did some FTP test between PC-NAS. FTP protocol is NOT "multichannel", so my expectations are READ 300 MB/s and WRITE 300 MB/s for LAN1 and the same numbers for LAN2. The FTP test confirmed my expectations, the same max speed in case of downloading and uploading. Success, my hardware works correctly.

4

Because of success in point 3, I checked the configuration like this-> SMB multichannel OFF. According to FTP test the results should be more or less the same for SMB without "multichannel" feature. Again the results disappointed me, on LAN1 downloading speed was 200 MB/s vs uploading 300 MB/s, the same numbers on LAN2. It means that SMB protocol does not work correctly on Windows 11 PRO 22H2 at all. It doesn't matter SMB multichannel is ON or OFF the SMB downloading speed is disaster.

Postscript

To test FTP and SMB I used my main drive C (PCIe NVMe SSD drive) and also RAM Disk (memory 16GB ram disk). The results are exactly the same. So, the performance of destination disk (write operation in downloading tests) does not matter. It seems to be a huge SMB bug...

What do You think about my tests, maybe something is wrong in my approach ?

UPDATE

Windows 10 Home installation from scratch + newest NICs PC drivers -> OK, no SMB multichannel transfer issues, about 550-560 MB/s transfer speed for uploading and downloading too !

Windows 11 Home installation from scratch + newest NICs PC drivers -> Not OK, still problem with SMB protocol and SMB multichannel speed transfer (downloading). It seems to be problem with SMB on Windows 11.

UPDATE

Unfortunately, upgrading "clean" environment of Windows 10 to Windows 11 destroys Windows environment. After updating to Windows 11 the problem with SMB reappeared.

Hello, good to know, I investigated problem myself, the Windows 11 fix is needed to resolve the issue.

Same issue here. I just created a dual boot scenario with Ubuntu 22.10 and the smb problems went away completely. This tells me it is Windows 11 22h2.

My hardware is a MSI GS76 Stealth laptop and I am connecting to a Synology DS-1821+ NAS. SMB is completely broke. Large files wont transfer, small files take forever. Transfer speed is painfully slow at 355KB/s for a 59MB file, and most times I cannot even get it to start. Nas to Windows transfer as expected around 15MB/s. One other thing. Transferring from Windows to my NAS over a web browser is affected too.

Sure would be nice for Microsoft to fix this fast. Has completely broke my network.

There are some workarounds mentioned in the notes, and they are working to resolve the issue.

Xcopy with the /J option to bypass the buffer failed. Same results as SMB. I am tired of troubleshooting Microsoft's errors so I didn't try robocopy. I just want my software fixed. SMH. Probably just going to switch back to Linux permanently and use a KVM session of Windows 10 to use my Windows software. Only reason I went back to Windows was due to my new laptop. I wanted to leave it OOB for warranty purposes. Actually appreciated some of the newer features, such as Linux sessions with graphical capabilities natively displayed in Windows provided by WSL2. Microsoft breaking SMB for over 2 months now is just too big of a fubar for me to ignore, and has caused me time troubleshooting to pinpoint which side of the aisle caused the problem. Time is precious.

I've just learned some new information regarding Win11 update KB5022303, quoting from another thread:

"It does not effect SMB multi-channel and in fact Microsoft already has a patch available on the release preview build from December, it turns out that the issue is not related to SMB, but does effect file transfers with older drivers that were meant for Windows 10, but are being used on Windows 11."

It's a thread on Synology's website which I will copy here in case others want to follow: