Bad Network Performance in Windows 11 guest with VirtIO Ethernet Adapter

[nison]

Recently I've migrated some VMs on ESXi to proxmox and now I'm facing on network performance issue on Windows 11 VM.

For comparison, I've used these machines for speed testing:

• proxmox bare-metal node
• Windows 11 VM (has network performance issue)
• Windows Server 2019 VM

And the results are shown below:

From	Destination	Method	Download Speed	Upload Speed
proxmox node	Ookla Speedtest (id: 48463)	Ookla speedtest CLI	7350.48 Mbps​	6683.27 Mbps​
Windows 11 VM	Ookla Speedtest (id: 48463)	Ookla speedtest CLI	753.44 Mbps​	2541.27 Mbps​
Windows Server 2019 VM	Ookla Speedtest (id: 48463)	Ookla speedtest CLI	7037.86 Mbps​	4885.08 Mbps​
Windows 11 VM	proxmox node	iperf3	1.11 Gbits/sec​	2.51 Gbits/sec​
Windows Server 2019 VM	proxmox node	iperf3	7.11 Gbits/sec​	8.49 Gbits/sec​
Windows 11 VM	Windows Server 2019 VM	iperf3	1.15 Gbits/sec​	1.58 Gbits/sec​

As you see, the Internet connection is capable of multi-gigabits ethernet, but performance in Win11 VM is quite low.
Could you find any cause of this problem?

Both Win11 and WinServer2019 VMs are migrated from ESXi and have "Red Hat VirtIO Ethernet Adapter".

The only difference between them is ... Windows 11 VM has a PCI passthrough device: GPU and USB Controller.

 

[_gabriel]

try with baremetal clean Windows 11 install

 

[RoelVB]

Were you ever able to figure this out?
I have some Windows server VM's (2012r2 and 2016) that do over 10Gbps, but my Win11 VM rarely reaches 2Gbps

Edit:
Ooh.. this user had never been online after the original post

 

[RoelVB]

I case someone else encounters this. My issue had nothing to do with Proxmox.
Turned out that Glasswire running on this VM was the issue, upgrading Glasswire v2 to v3 made me hit 10Gbps (Glasswire couldn't automatically update from 2 to 3)