Slow WAN speed on upgrade 2.6.0

RMH 0

@mxkied2 Sorry, I did not notice posting messed up the commands ran. I should have posted a screen shot of when I ran it. :(

mxkied2

@rmh-0

No worries at all, it did the same thing to me as you can see from the edits above. HUGE THANK YOU for finding a fix and posting it!

GrimmSh0t

@rmh-0

Here you go :

berbec

@grimmsh0t I just did this on my machine:

PS C:\Users\Administrator> Get-VMSwitch -Name * | Select-Object *RSC*

SoftwareRscEnabled
------------------
              True
             False
              True
              True
              True

PS C:\Users\Administrator> Set-VMSwitch -Name * -EnableSoftwareRsc $false
Set-VMSwitch : Failed while modifying virtual Ethernet switch connection settings.
At line:1 char:1
+ Set-VMSwitch -Name * -EnableSoftwareRsc $false
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [Set-VMSwitch], VirtualizationException
    + FullyQualifiedErrorId : OperationFailed,Microsoft.HyperV.PowerShell.Commands.SetVMSwitch

PS C:\Users\Administrator> Get-VMSwitch -Name * | Select-Object *RSC*

SoftwareRscEnabled
------------------
             False
             False
             False
             False
             False

Despite the error, it looks like using an * as the -Name option works. EDIT Error looks safe to ignore.

So that leaves us with one command to disable RSC and one commands to check the setting, assuming you don't have any vSwitches that need RSC:

Check: Get-VMSwitch -Name * | Select-Object *RSC*

Disable: Set-VMSwitch -Name * -EnableSoftwareRsc $false

I will upgrade to 2.6.0 tonight and report if this fixes the issue.

EDIT: I figured out why I was getting an error. I have a Private vSwitch, and that one can't have RSC enabled. The error would not have occured for normal vSwitches attached to ports on a Ethernet card.

hac76

@rmh-0 Thanks a lot, working for me too !

ITEM93

@rmh-0
Thanks so much for posting this!
I can confirm that this fix worked for us as well!

jvansyoc

Windows Hyper-V 2019
Windows 10 VM behind PFsense 2.6.0

https://www.doitfixit.com/blog/2020/01/15/slow-network-speed-with-hyper-v-virtual-machines-on-windows-server-server-2019/

No restart required

joez34

A little late to the party here, but I can confirm that this is an issue in Server 2022 on a Dell R440
Disabling RSC also fixes the issue.

tharun518

Just want to share my experience on Windows Server 2022.

Updating OS to latest version didn't fix it.

Disabling RSC improved network performance. Download speed was pretty good, but upload was stuck at 65mbps and response time was worst.

Only switching to ver 2.5.2 truly fixed my problem and getting 1gbps up/down now.

tischenkod

A solved same problem by tunring on "Disable hardware TCP segmentation offload" and "Disable hardware large receive offload" options in System->Advanced->Networking