5

I have the weirdest problem I was hoping you could help me with. I've got a dedicated Server 2012R2 server with an Intel 82580 network adapter. It runs a couple of VMs in Hyper-V that are attached to an Internal virtual switch. This switch is then NATted to various IP addresses on the real interface of the server.

I've currently got two guests running, an Ubuntu guest and a Server 2008R2 guest. Both get really good download speed (90Mbps, about what the dedicated server gets) but the upload speed is really bad. The dedicated server has an upload speed of about 60Mbps, the 2008R2 VM gets about 5Mbit and the Linux VM gets a speed too low to measure, the test just reads 0.00Mbit.

Does anyone know what the issue could be here? I've tried disabling VMQ, disabling IPv4 checksum offloading and disabling IPsec task offloading, none of which made any difference what-so-ever.

Guzzlebot
  • 141

5 Answers5

9

I appear to have solved the issue by disabling large send offloading in the guest operating systems. Disabling it on the host didn't help but disabling it on the guests solved the issue.

Guzzlebot
  • 141
4

This answer is still relevant. My case: Windows 10 Host, Windows 11 guest. Upload was slow, had to disable "large send offloading" on the windows 11 VM to have full upload capabilities.

Go to the "network connections", choose the Ethernet connection, "Properties" > "Configure" > "Advanced"

enter image description here

Jens Caasen
  • 141
  • 1
1

For Windows 10 21h1 this worked for me: PICUTRE:

Windoof93
  • 11
1

Disabling on the host and guest can sometimes fix this. To disable it on an Ubuntu 22 guest, do the following:

`sudo nano /etc/network/if-up.d/disable-lro.s`

then add this to that file:

#!/bin/sh
ethtool -K eth0 lro off

Make sure the permissions are correct:

sudo chmod +x /etc/network/if-up.d/disable-lro.sh

Then reboot Ubuntu.

gabeyww
  • 11
0

This ultimately worked for me:

sudo apt install ethtool
sudo ethtool -K eth0 tso off

You can check whether it worked by running:

sudo ethtool -k eth0 | grep 'tcp-segmentation-offload'
wget -O - https://raw.githubusercontent.com/sivel/speedtest-cli/master/speedtest.py | python

I now get the full upload speed of my ISP, which is 40:

pic of upload speed

gabeyww
  • 11