VMware to Proxmox migration - network performance Windows 2019 slow

[dhadderingh]

We have migrated a Windows 2019 VM from VMware to Proxmox using VEEAM. The VM is running with the VMware tools deinstalled and the VirtIO drivers installed. CPU is configured to "host". The network adapter is "VirtIO".

The issue that we have is that network performance from the Windows VM is very slow. So copying to and from the different Windows 2019 VM's is very slow (50Mbit max). Using iperf from the VM to the proxmox host is a bit faster (250Mbit max).

We installed a completely new Windows 2019 VM and that machines is not having any issues with network performance. The iperf connection from that VM to the Proxmox host and another Proxmox cluster host is line speed.

Anyone got any ideas?

 

[Johannes S]

I guess you know already https://pve.proxmox.com/wiki/Windows_2019_guest_best_practices but that page recommend setting the network adapter "VirtIO (paravirtualized" not "VirtIO":

• Configure your memory settings as needed, continue and set "VirtIO (paravirtualized)" as network device, finish your VM creation.

Another reason for subpar performance on a Windows guest might be some security-related mitigations of Windows for CPU bugs, in that case changing the CPU type from host to another one should help: https://forum.proxmox.com/threads/t...-of-windows-when-the-cpu-type-is-host.163114/

But since that problem is CPU specific I doubt that there is any relation. Just mentioned it to be safe

 

[dhadderingh]

I've found the problem. It seems to be the installation of Symantec Endpoint Security. After deinstallation the network speed is as it should be. After reinstallation (new version) the speed stays like it should.