Windows copy slow

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Windows copy slow

L1 Bithead



We have an SDWAN deployment of 30+ sites using PanOS 10.2.4-h2 and have WAN links using PPPoE.


We are having reports of slow copying of files back to our Data Centre using Windows copy (Windows 10/11, Windows Defender).

Most WAN links are 100Mb+, but we are only getting <500kbps from a site that has a 1Gb Internet link.

We have disabled Server Response Inspection for SMBv3 and set an application override as well.

As a side issue users report opening up the file via Windows Explorer is incredibly slow.


Any pointers would be appreciated.


L2 Linker

Sounds like NGFW is involved in allowing your flows.  "Try disabling multichannel on the Windows server and client. Because of the way that SMBv3 multi-channel works in splitting up files Palo Alto Networks recommends disabling SMB multi-channel through the Windows PowerShell."   This advice comes from this article -- Why is SMB traffic slow ? (

Have you seen this article on SMBv3 multi-channeling? 

Douglas Elliott
Security Implementation Engineer

Thanks for the suggestion.

Latest is we ran up a new instance of a Windows client in a sandbox and the results were chalk and cheese, so there is something specific in our build that is causing the issue.


Not sure if it is Windows Defender or one of the myriad of Group Policies.  We are currently narrowing that down before we proceed further but I will look further into your suggestion.


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