What should I do if the network speed of Win10 Hyper-V virtual machine is slow? How to solve the slow network speed of Win10 Hyper virtual machine

php editor Banana will introduce to you how to solve the problem of slow network speed of Win10 Hyper-V virtual machine. When using a Win10 Hyper-V virtual machine, we sometimes encounter slow network speeds, which affects our work efficiency and experience. Don’t worry, there are some simple steps we can take to fix this problem. Below are some common solutions, I hope they can be helpful to everyone.

How to solve the slow network speed of Win10 Hyper virtual machine

1. First of all, you should pay attention to the receiving segment that appears in Hyper-V on Windows Server 2019/2022 (and Windows 10 1809) Merge (RSC) function. Receive segment coalescence is used at the virtual switch level (vSwitch).

2. RSC allows reducing CPU load and increasing network throughput by combining multiple TCP segments into larger segments. Network performance is improved because large segments are processed faster than many smaller segments.

3. In previous Hyper-V versions (Windows Server 2016/2012R2), only hardware receive segment merging mode was supported at the NIC level.

If RSC support is enabled, it may cause additional network latency in some hardware configurations. By default, all external switches on Windows Server 2019 have RSC enabled.

You can check if RSC is enabled for the virtual switch using the following command:

Get-VMSwitch | Select-Object *RSC*

You can disable it for the client using the following command IPv4 traffic on the network adapter uses RSC:

Disable-NetAdapterRsc -Name “Ethernet” -IPv4

Check if the replication speed in the Hyper-V VM increases after disabling RSC. If network speeds improve, RSC can be disabled on the virtual switch to which the VM is connected.

4. You can use the iperf tool to check the network throughput.

1) To disable software RSC for a specific virtual switch, run the following command:

Set-VMSwitch -Name vSwitchName -EnableSoftwareRsc $false

You can enable/disable on the fly RSC, it does not affect any active connections.

Alternatively, you can disable RSC completely on the Windows host:

netsh int tcp set global rsc=disabled

2) Network Virtual Machine Queue (VMQ) Mode in Adapter Driver

In some cases, if VMQ (Virtual Machine Queue) is enabled in the network adapter driver of the physical Hyper-V host, this may cause Poor network performance in Hyper-V virtual machines.

VMQ is a hardware feature and if your hardware does not support it enabling it in the driver may result in packet loss and increased network latency.

This issue is typical of Broadcom Gigabit Network Adapters and occurs in all Hyper-V versions (Windows Server 2012 R2/2016/2019).

VMQ is designed to improve network performance by forwarding packets directly from physical network adapters to virtual machines.

VMQ can be disabled in the properties of the network adapter driver.

Alternatively, you can use PowerShell to display a list of network adapters that support VMQ and their status:

Get-NetAdapterVmq

5. To disable VMQ for a specific network card, run the following command (the network adapter will be unavailable for a few seconds):

Set-NetAdapterVmq -Name "NICName" -Enabled $False

After disabling VMQ, It's a good idea to reboot the host and check network performance.

#6. Make sure to disable the

QoS bandwidth limiting policy in Windows.

7. Optimize Hyper-V’s TCP settings on Windows Server 2019

1) Save the current TCP settings on the Hyper-V host and apply the new settings, which will make TCP settings in Windows Server 2019 are almost similar to those in Windows Server 2016.

2) Save the current settings:

Get-NetTCPSetting -SettingName Datacenter, DatacenterCustom, InternetCustom, Internet|select SettingName, CongestionProvider, CwndRestart, ForceWS|Export-csv c:\backup\ws2019_network_stack_settings_nettcp_backup. csv

8. By default, in Windows Server 2019 and Windows 10 1709, the CUTRIC implementation of TCP is used. This algorithm is optimized for high-speed networks with high latency (it is also used by default in Linux kernel 2.6.19 and later).

Apply the following settings only in Windows Server 2019 or Hyper-V 2019.

1) Apply new NetTCP settings for the LAN:

Set-NetTCPSetting -SettingName DatacenterCustom, Datacenter -CongestionProvider DCTCP

Set-NetTCPSetting -SettingName DatacenterCustom, Datacenter -CwndRestart True

Set-NetTCPSetting -SettingName DatacenterCustom, Datacenter -ForceWS Disabled

2) For WAN:

Set- NetTCPSetting -SettingName InternetCustom, Internet -CongestionProvider CTCP

Set-NetTCPSetting -SettingName InternetCustom, Internet -DelayedAckTimeoutMs 50

Set-NetTCPSetting -SettingName InternetCustom,Internet -ForceWS Disabled

3 ) Disable network RSS and RSC at the TCP stack level Network optimization method:

netsh int tcp show global

netsh int tcp set global RSS=Disabled

netsh int tcp set global RSC=Disabled

4) or at the network card level:

Get-NetAdapter | Set-NetAdapterAdvancedProperty -DisplayName “Recv Segment Coalescing (IPv4)” -DisplayValue “Disabled” -NoRestart

Get-NetAdapter | Set-NetAdapterAdvancedProperty -DisplayName “Recv Segment Coalescing (IPv6)” -DisplayValue “Disabled” -NoRestart

Get-NetAdapter | Set-NetAdapterAdvancedProperty -DisplayName “Receive Side Scaling” -DisplayValue “Disabled ” –NoRestart

Disable vRSS for all virtual machines:

Get-VM | Set-VMNetworkAdapter -VrssEnabled $FALSE

5) Disable Large Send Offload (LSO) on the network card ):

Get-NetAdapter | Set-NetAdapterAdvancedProperty -DisplayName “Large Send Offload Version 2 (IPv4)” -DisplayValue “Disabled” -NoRestart

Get-NetAdapter | Set-NetAdapterAdvancedProperty -DisplayName “ Large Send Offload Version 2 (IPv6)” -DisplayValue “Disabled” -NoRestart

Get-NetAdapter | Restart-NetAdapter

9. You can also select the “Advanced” tab of the network adapter properties Disable these options in:

Receive Segment Merging (IPv4/IPv6) = Disabled

Large Send Offload v2 (IPv4/IPv6) = Disabled

These TCP stack settings will Make Windows Server 2019 network protocol settings similar to previous Windows Server versions.

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