Slow wired upload speed vs Linux on same hardware

Question

Intel® Ethernet Controller X550-AT2, 10G network interface on ASRock Rack ROMED8-2T with AMD EPYC 7232P processor.
Windows 10 Pro for Workstations, 2004.
Latest Windows updates and Intel drivers installed as of 09/09/2020.

This machine is a dual boot, the above Windows version, and Ubuntu 20.04.
When doing a speed test, I get good performance from Ubuntu, but very poor uploads from Windows. This is on the same machine, the exact same hardware.

The WAN link is 1000Mbps down, 50Mbps up.

This is the Windows speedtest result:

This is the Ubuntu speedtest result:

I have tried to tweak the adapter's advanced driver settings in Windows, such as disabling LSO, etc. No luck, performance remains poor.

I've also noticed it on another PC running Windows 10 Pro, and a laptop running Windows 10 Pro for Workstations, both give the same poor upload performance. Whereas my other Ubuntu 20.04 Server machine, and also my phone connected via Wi-Fi, is getting good upload speeds.

I have even taken the Windows laptop and plugged it straight into my incoming WAN connection (bypassing router), and it still gets poor upload speeds.

Incidentally, when the speed test is running, I can see that the upload looks bursty on Windows, like it is only getting chunks of data here and there, while in Linux and on Android it looks the same as the download, the graph is drawn at a consistent high rate and with consistent high values.

Answer 1

Hello @mensa84 ,

I wrote "I would guess" and "Further guesses are" - I don't "know" that any of my assertions are true.

Previously, the registry entry "TcpMaxDupAcks" was used to influence the behaviour that I described; see Description of Windows TCP features (key text reproduced below). Windows now seems to be moving to the techniques described in The RACK-TLP loss detection algorithm for TCP, but it doesn't seem to be working perfectly yet - this might be part of the reason why an update resulted in poorer performance - but that is just a guess too.

[Oops - I read you message incorrectly regarding updates] It may just be the case that new equipment in the network increased the amount of re-ordering that is taking place - pushing it beyond the manageable level. Pure conjecture, but perhaps Huawei equipment in the 5G network was swapped out for Nokia...

By default, Windows resends a segment if it receives three ACKs for the same sequence number (one ACK and two duplicates) and that sequence number lags the current one. This is controllable with the TcpMaxDupAcks registry parameter.

The TcpMaxDupAcks value in the following registry key can be edited to control the number of ACKs necessary to start a fast retransmits:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters

Gary

Answer 2

I have the same issue.

under windows 10 (latest updates), max upload is about 6-7mbps

an android emulator under windows gives me about 30mbps up

the same machine booted into Linux is about 50-60mbps up

iPhone also clocks in at about 50-60mbps up and similarly iMac

fastest upload speed recorded (not sure which machine), was about 100mbps up, so the link is capable of much higher speeds...

and all are about 80-100mbps download

my internet connection is not limited or throttled at a certain rate, it is an 8-mile microwave link, and varies a bit, yet never got any lost packets.

I tried everything in this (and other guides, which give similar instructions) and no change for windows, yet the android emulator upload is now only 20mbps...

Answer 3

Hi,
if you have already tried all the suggestions that have been proposed here to no avail, you can try this path:
Settings> Update & Security> Advanced Options> Delivery Optimization> Advanced Options> Download / Upload Settings, move the slider of the different items to higher percentages or according to your needs.

Answer 4

Hi,

Thanks for your feedback.

If the issue still existed after updating settings per above suggestions, collecting network traffics should be necessary for further investigating. However, analysis of network traffic is beyond our forum support level. So I would suggest you contact Microsoft Customer Support and Services where more in-depth investigation can be done so that you would get a more satisfying explanation and solution to this issue.

You may find phone number for your region accordingly from the link below:
https://support.microsoft.com/en-us/help/4051701/global-customer-service-phone-numbers

Best Regards,
Sunny

============================================

If the Answer is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Answer 5

Hi,

let me add also some hints from my side - I've found this articel by googling around for nearly the same problem.

I'm having a Desktop having an Intel X520 Adapter - 2x SFP+ 10 GB connections connected to a Switch.

In the context of upgrading my Internet Modem to a FritzBox using Vodafone Kabel 1000/50 connection, was all working out fine testing it on my Mac. But once I've checked it on my Windows System I've noticed wired upload limit of 4mbit.

As I've changed Internet devices I was assuming that the Problem comes from that angel - and I've changed the Modem/Fritzbox as well as my UDM Pro (Gateway) and so on all back and forth.
And then there was one major observation: Testing the connection from PC -> Switch -> UDMPro -> FritzBox as Bridge --> I've got my full 50mbit Upload
Testing it again with PC -> Switch -> UDM Pro -> FritzBox with UDM as Exposed Host --> I'm getting only 4mbit Upload

Ok, so I thought it is about NAT Translation; Wrong UDM configuration and so on - and I've researched and tested a full day on that - but hold on - all other devices; PS4; iPhone, Mac, Apple TV and mabBook pro - all devices are working fine and getting 50mbit up using the FritzBox with the UDM as Exposed Host? This was making me 'nervous' and I've starte looking closer into my Windows system.

So I've kept the setup using the UDM Pro as exposed host on the Fritzbox:

1. I've connected my onboard Realtec 1Gbit Lan to the UDM Pro integrated switch - and bam - I was getting full 50mbit upload
2. I've then tested again my 20Gig x520 aggregated connection - and - no, only getting 4mbit;
3. I've split my aggregated nic again into 2x 10gig connection (both on the same physical x520 nic adapter) and tested adapter 1 - and - no, only getting 4mbit upload
4. Then tested adapter 2 of the x520 nic - and - boom, full 50mbit upload

So at that point in time, it was clear one of the two 10GBit Adapter of the x520 card causes by what ever reason that the upload is limited to 4mbit.

I've exchanged of the adapter wich was able to upload the 50mbit the transiver as well as the fibre cable which was prooven as working - and no diffrence; still the adapter 1 is imited to 4mbit upload.

Then I rembered that I was already able to get day's earlier also full 50mbit upload; but using the bridge mode - so I've retested it activly again.
Changing my UDM Pro connecting to the Bridge mode of the FB and having an external IP -> and boom, the adapter 1 is now also showing full 50mbit upload.

I've changed it now back and forth - and it is fully reproducalbe:

Using UDM Pro with external IP: x520 Adapter 1 and x520 Adapter 2 both capable of having up to 50mbit upload speed.
Using UDM Pro as Exposed Host: x520 Adapter 1 limited to 4mbit upload while Adapter 2 is able to upload fully with 50mbit.

Remark:
I've tested the upload using wieistmeineip.de - nperf shows alway 50mbit upload, but lies - Trying uploading to google/icloud only come up to 4mbit. So I stick to wieistmeineip.de for continous testing.

In conclusion: I have no idea what is that causing; amount of hopps, some kind of ttl or something similar - I don't know. As the x520 is somehow working I can't emagine that it is a Windows OS problem - but on the other side, I've checked all possible adapter settings of the x520 adapter 1 and x520 adpater 2 - compared them and so on - all looks identifcal, but behaves diffrently - also unistalling/reinstalling drivers is not making any diffrence.

As said, I'm not having a idea of the root cause; but maybe someone of you can bring this explanation in a 'more' accurate context and it helps.

I'll start now enhancing my skills using wireshark and who knows... maybe... I've I'll find something I'll share it here in addition.