Network speed is very slow in Win11 VM

Hey all,

I'm looking for some suggestions to improve my network/Internet speed. For testing, I just did a simple test using speedtest.net to gauge my Internet speed. In my host OS, my network speed is about 2.3Gbps down and 350Mbps up. In my fresh Win11 VM, I am getting about 300Mbps down and 320Mbps up.

I am currently running Parallels 20.0.1 (55659). I have tested this with both Win11 Pro x64 and Win11 Enterprise x64. Both have pretty similar numbers.

Here's what I have tried:

• In Win11, set Offload Tx LSO to disabled for the Parallel's virtual NIC
• Set Parallels config Optimization to No Limit
• In Parallels config, I tried every setting for Network including Network Conditioner-Custom-unlimited/unlimited. The fastest option from my testing appear to be Default Adapter
• In the Win11 VM, set the Services-QoS-Throttle rate to 0. I know this isn't really tied to overall performance but is an option I tried.

Are there other options I can try? I know there will be some overhead when traversing VMs but this discrepancy is well outside of what I was expecting.

 

All, I just wanted to add that in discussions with Support they had me remove and re-add the Network adapter for the Win11 config. I set the adapter to "Default Adapter" and re-tested. This, alone, bumped my network speed to about 800Mbps. I am still investigating if we can get the speed closer to the host network speed but this was a significant bump.

 

Hi ErikT5, I'm having similar problems with 20.1.0
I have a symetrical 1Gb full fibre connection, and in Mac OS via Firefox I can get full speed, but in Win11 via Firefox, I only
see 150-200 Mb up and down.
Can you explain about removing the network adaptor, do you mean right click on the Intel(R) PRO/1000 Network Connection and uninstall it?

 

Sure thing. You should be able to follow these steps:

1. Shutdown your Windows VM
2. Open Control Center (you can right-click on the Parallels icon in the taskbar)
3. click the configuration gear on the Windows VM.
4. Under Networking, add a new adapter by hitting the + in the lower left of the configuration dialog (don't delete your old one yet). With the new adapter, test the speed. If it looks good, you can go back and delete the old adapter (select it and then click the - button).

Now, that said, I have been working with support and there was another trick they had me do that added about another 100Mbps to the overall download speeds. It's a bit more involved but was worth it for me. Note that we are still investigating to see if we can get higher speeds but right now I am sitting around 920Mbps down and 350Mbps up

1. Click on the Apple menu in the top-left corner of your screen and select "System Settings"
2. In the System Settings window, click on "Network."
3. Select the network connection for which you want to disable IPv6 from the list on the left. It could be Ethernet, Wi-Fi, or any other active network connection.
4. Click on the "Details" button.
5. In the Advanced settings, navigate to the "TCP/IP" tab.
6. From the "Configure IPv6" dropdown menu, select "Link-local Only" or "Off".
7. Click on the "OK" button to apply the changes.
8. Start your virtual machine.
9. On your Windows virtual machine, Press Windows + R to open up a Run dialog box. -> Type "control panel" in the Run box and press the Enter button to open it.
10. Click on "View network status and tasks"
11. On the left side of the Network and sharing center window, click "Change adapter settings".
12. Right-click your network adapter and click on Properties.
13. Uncheck the Internet Protocol Version 6 (TCP/IPv6) option and click the OK button.
14. Open Parallels Desktop > Right-click on the Parallels Icon in the Dock > Control Center > Right-click on your Windows virtual machine > Configure
15. Select "Hardware" > Network > Advanced > Open Network Preferences > Select IPV6 tab > Untick "Enable IPv6 DHCP > Apply
16. Launch your virtual machine and try to reproduce the issue.

 

Thanks for that information, I tried all the suggestions but it didn't really improve my problem.
As per the above messages, the support team are now helping me and hopefully will be able to suggest a fix.

 

Are my emails getting through to you?
This is what I replied to support emails.....
Hi Trishna,

I tried to follow those instructions, but when I type 'pktmon stop' into the cmd window
I get the response "Failed to obtain Packet Monitor status: The system cannot find the file specified."
Do I have to issue a command to start the packet monitor?

Also if it had worked, where would I look for the log files?

Best regards,
Kevin.


On 19/10/2024 17:27, Trishna Oobeyram wrote:
Hello,

Thank you for your email.

In order to investigate your issue further, please perform the steps below to collect log data:

a. Start Parallels Desktop and your virtual machine.
b. Go to Finder > Applications > Utilities > Terminal.
c. On your host Mac, launch Terminal (Finder > Applications > Utilities > Terminal) and execute the following command:

prlsrvctl set --verbose-log on

d. Once the issue occurs.
e. On your host Mac, launch Terminal (Finder > Applications > Utilities > Terminal) and execute the following command:

sudo tcpdump -i all -w net-host.pcap

f. While the command is running on your host machine, in your virtual machine, once the issue occurs. (if the network is down, try to access random network resources)
g. Press Command + R to open up a Run dialog box. Then, type CMD and then press CTRL + SHIFT + ENTER., and execute the following commands.

pktmon stop


pktmon etl2pcap C:\PktMon.etl --out net-guest.pcap

h. Wait until the command terminates.
i. Terminate the command running in step (e) by pressing the CTRL + c key combination.
j. The net-host.pcap and net-guest.pcap files will be generated on both your host and guest.
k. Kindly upload both files to the secure file-sharing link provided below.

https://fe.parallels.com/8b66a64bd38670be732d68ba979c262e/

Please let us know the results after performing the above steps.

 

Well, that was a complete waste of time.
I answered the emails support sent as I posted above, but got no response.
All I got were emails asking if everything was good, and then one asking for me to review their help.

Needless to say, itwas a negative review!

 

I had the same problem and ended up reinstalling Windows. Everything seemed fine until I finally wanted to start downloading Visual Studio. At that moment, I found out that the situation was repeating itself. The download speed dropped to hundreds of kilobits instead of hundreds of megabits... But at that moment I remembered what I did last in Parallels settings for the virtual machine. I set the optimization to medium! So i reverted the setting to "no optimization" and there it is, internet speed is back to normal.

 

Hi JurajF, unfortunately, my Optimisation setting is already at No Limit.
But thanks for helping.

 

I've had slow download/uploads, and at times "You are not connected to the Internet" type errors. Smallish Steam games would take 40 minutes to download, and at times time out due to slow network.

I finally set the Parallels/Hardware/Network to "Default Adaptor" rather than "Shared Network (recommended)". I have run it this way for a few months with no problem (I'd even forgotten that I made this change until reading your post).

Somewhere along the way the shared network seems to have become problematic.

 

Thanks megavolt17, but I've tried all of the different settings and none give me my full capablity.
I did try a different browser, Vivaldi, which weirdly sometimes gives me full UPLOAD speed, but DOWNLOAD stays
doggedly at around 220 ish Mb. Even tried Edge (shudder) and got the same results as Firefox.

 

Hey All.
I had the same problem for a long time.
Try the below steps and hopefully will work for you:
1- Shut down the windows.
2- Go to the Gear.
3- Hardware -> Network -> Source (Wifi) -> Tick Network Conditioner (Custom)
Thanks.

 

Hi TamerB,
Thanks, just tried that but unfortunately it didn't work

 

See https://forum.parallels.com/threads...ter-on-mac-os-so-slow-using-parallels.344397/

Confirming that this is the problem and is a Parallels reproducible bug. It is insidious in the latest version of Parallels 20.2.0, build 55872, in that Resource usage changes after windows ot the mac goes to sleep, even if configure is locked! Sequoia 15.2 (24C101), Macbook Pro M3, Windows 11 ARM, all fully updated.

Workaround 1. Always shutdown Windows before letting mac go to sleep. Workaround 2. Run MS Edge at VM boot, the ookla. If slow, open configure, then set Optimization to No limit and reboot. So far, the two workarounds 1 and/or 2 have worked most if not all of the time, although I have rebooted the Mac and VM so much just to be able to work, I can't vouch that this works with it works in all situations. It has helped to always perform Workaound 2 before doing any work.

I get the same speeds with VM Edge and Mac Safari or Firefox

 

I had this issue as well, got to poking around in Actions --> Configure --> Options --> Travel Mode --> Changed "Enter Automatically" and "Quit Automatically" to never. "Enter" was set to "Always when on battery power," and "Quit" was set to "When connected to power." Even though I was connected to power at the time, Parallels was still throttling my network bandwidth. Turning this feature back on brings the issue back.

 

Travel Mode no longer supported from 19.3.0so I am unable to try that.
I still have the problem, but weirdly, Edge sometimes works at full speed in tests when Firefox doesn't.
But other times Edge only give me 21Mb ish (of my 1Gb fibre) download like Firefox.

 

For me it was the optimization feature I had to turn off. Thanks for the inputs here.

 

None of these suggested workarounds gives me the full download speed available on the Mac side.
Mac Firefox gives up 870Mb download Mac Safari shows 820Mb, but Win 11 side Edge 650max Firefox 200 and
Vivaldi 200 or so too.
Computer going to sleep and waking up doesn't seem to make any difference to a fresh boot.