Slow SMB File Transfer (Win11)

Question

I have 3 Win11 PCs and 2 Win 10 PCs on a home network, all running on 1Gb ethernet. I have two ethernet NAS drives on the network. All of the computers run fine and I obtain file transfer rates around 100GBs, as expected for a 1Gbs network.

I recently purchased and set up a new PC with Win11Pro. Everything seems fine with it, but for some reason I cannot figure out it only gets 12GBs file transfer speeds when accessing either of the two NAS devices. The ethernet ports are fine and I get Internet download speeds of 1000Gbs, but any SMB file transfers are stuck at 100Gbs. I can even run the network monitor which shows 100Gbs when copying the file, then I ask for an Internet speed test and the transfer rate shoots up to 1000Gbs, then when I kill the speed test it drops back down to 100Gbs.

There seems to be something throttling the SMB file transfer, but ONLY to that one computer. All the rest are as expected. It is a new computer, just set up. I've already done a Windows re-install. I have pored all over the network settings and compared them to one of the PCs that works. I've not done anything to the default settings. It doesn't matter whether I connect it via a switch or directly to the router that has the NAS devices connected.

I'm out of ideas at this point, especially since cabling and switches and NIC problems seem to be ruled out because Internet download speeds are fine, and the NAS servers happily tranfer at 1000Gbs to all the other computers.

Answer 1

Hi, thanks for posting here in Microsoft community, since your NAS doesn’t support encryption and Get-SmbConnection didn’t show encryption info, it’s likely not enforced. Disabling SMB signing was a good step. Next, try checking if SMB compression is enabled and it can also slow transfers. You can check this via PowerShell:

Get-SmbClientConfiguration | Select EnableCompression

You can consider updating your NIC driver and checking for hidden advanced settings via Device Manager > NIC > Advanced tab.

 

Also, have you tried transferring files between this new PC and another Windows PC (not the NAS) to see if the slowdown is specific to the NAS or affects all SMB traffic?

 

Chard

Answer 2

Thanks for posting here in Microsoft community, it sounds like your new Win11 Pro PC is throttling SMB file transfers despite having full internet bandwidth and identical network settings to other PCs. Since hardware and cabling are ruled out, this could be due to SMB signing or encryption being enabled by default on the new PC, which can slow down transfers, Network adapter settings like “Large Send Offload” or “Auto-negotiation” behaving differently and QoS policies or group policies affecting SMB traffic.

Try disabling SMB signing/encryption temporarily and check advanced NIC settings for offload features.

Also, have you checked if SMB signing or encryption is enabled on the new PC compared to the others?

I hope this helps you out, let me know how it goes.

Chard

Answer 3

Thanks for the update! Since your NAS is an older WD MyCloud and likely doesn’t support SMB encryption, the slowdown might be due to your new Windows 11 PC enforcing SMB encryption by default. This can significantly reduce transfer speeds, especially with older devices.

To check if SMB encryption is enabled on your Windows 11 PC, to do this simply, Open PowerShell as Administrator then run

Get-SmbConnection

Then look for the Encrypted column. If it says True, encryption is active.

Then to disable SMB encryption (for testing) then run

Set-SmbClientConfiguration -RequireSecuritySignature $false

Then test your file transfer speed again.

Also, double-check if SMB signing is enabled via Group Policy or registry it can also impact performance.

Chard