Windows 10: Intel X550-T1 on Windows: Very low throughput / slow transfer speed 10Gbe

Hi there,

I recently added a Intel X550-T1 NIC to my Windows machine. Now after doing some tests I noticed the throughput is only about 2.5 GBits/s using iperf3 for testing.

Same test performed using an Ubuntu Live Boot Stick yielded me a throughput of about 9 GBits/s.

Things I tried to improve:

- Completely re-installed Windows
- Installed the latest driver for the X550-T1 from the Intel website

What as well catched my mind: If I run the test with the loopback interface localhost as the target server, I only get the same poor throughput of about 2.5 GBits/s. All my Debian VMs and as well a Windows Server 2019 VM on an ESXi host are showing between 40-100 GBits/s in the same test. I as well booted from an Ubuntu Live Stick and was able to get 10Gbits/s here. So it definitely must have something to do with Windows itself.

Can anybody help me out please?

Best regards


Windows Version: Windows 10 Education 20H2

:)

 

Windows 10, 10gbe connection slow transfer, DefaultSendWindow / tcp

Hey

I did a bit of research on this matter and I'm pretty sure I have narrowed it down to windows DefaultSendWindow being set too low for modern networks.

Where can I edit this setting in windows to force a different tcp buffer length size.

I found this on internet TCP Window size problems


and this in that post
You can do that by editing the registry key:HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\AFD\Parameters\DefaultSendWindow

But this is empty on my end and I don't know what values I should put in to configure that.

A more 10gbe related topic on this I have posted on this forum, in case any1 is interested.
10gb SFP + network setup - slow windows TCP Transfer - Spiceworks

From my tests over there you can see that the windows is the issue of slow transfer speeds and not hardware/zfs/freenas.

Regards

 

Microsoft store download speeds and windows 10 app load speeds are very slow

Hi Riel,

• The latest update I have showing is "2018-02 Cumulative update for Windows 10 Version 1709 for x64 based system KB4074588"
• I've tried all the below steps suggested by Eeshwar Kumar in this link: Why is Windows Store's download speed so slow?
• And also all by Jane La in the below: Microsoft Store Very Low Download Speeds

Reuben

 

Slow network throughput on windows 10

======================
I have a 1Gbs LAN. Using Windows 8.1 Professional I was able to achieve (about) 100MB/sec speed to my Synology NAS. With install of Windows 10 Professional, speed dropped to (about) 10MB/sec. This article helped get file transfer speed back up to (about) 100MB/sec. Thank you, thank you.