Slow WAN speed on upgrade 2.6.0

RMH 0

I put this in another thread which may help here too

@rmh-0 said in After Upgrade inter (V)LAN communication is very slow on Hyper-V, for others WAN Speed is affected:

A bit of digging and it looks like 2 issues to me.

One in Hyper-V which I have now got resolved, fix below (well for me anyhow)
One in pfsense that is missreporting throughput (I can live with that till a fix comes)

For Hyper-V I found this article on RSC https://www.doitfixit.com/blog/2020/01/15/slow-network-speed-with-hyper-v-virtual-machines-on-windows-server-server-2019/
Once I disabled RSC on all virtual switches my speed was back to normal. No restart needed, just go on to Hyper-V host, open powershell and input commands to disable RSC on each virtual switch.

These are commands I used

Get-VMSwitch -Name LAN | Select-Object RSC
Checks status, if true run next command LAN is my vswitch name

Set-VMSwitch -Name LAN -EnableSoftwareRsc $false
This disables RSC, re run first command to confirm it is disabled

If your vSwitch has a space in the name add "" around the name
Get-VMSwitch -Name "WAN #1" | Select-Object RSC

After applying speed is back to normal but pfsense seems to top out showing throughput at 60mb, even though I was getting over 500mb.

Anyhow, hope it helps thers on Hyper-V (this is a 2019 instance of Hyper-V)

Dominixise

@rmh-0

I can confirm this method you list works on my server with hyper-v pfsense vm :)

Thanks thanks

Dom

mxkied2

Thank you @rmh-0

I can can also confirm this fixed the speed issues for me as well,

Only thing to note was that the command to check if RSC was enabled for me needed to include the wildcards

Get-VMSwitch -Name LAN | Select-Object RSC

needed to be

Get-VMSwitch -Name LAN | Select-Object asteriskshereRSCasteriskshere

otherwise I got no results. Just wanted to mention it.

Forum posting is removing the asterisks place asterisks before and after RSC in the get command

berbec

@mxkied2 the wildcards seem to have been eaten by markup. Is it an asterisk before and after RSC?

mxkied2

@berbec Yes, before and after

GrimmSh0t

@dominixise - I can confirm this works for me at least...Thanks for the post. Will do some more testing but for now running 2.6 with normal speeds.

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