strange vm network speed issue

Mar 3, 2020

I have a strange issue with my network on Proxmox 7.

When I use iperf between a connected PC and the Proxmox host, I get around 920-945 mbit/s.
Between the Proxmox host and a linux VM, I get 3-7 gbit/s. (everything correct so far)

But between the connected PC and the linux VM, i get only 600-780 mbit/s (most at the time 745 mbit/s).

With reverse option the result is the mostly the same with minor speed differences.

I tried it with the onboard RTL8111 nic, the pcie intel nic and usb nic --> same result
I tried it with the Pc directly connected to the Server instead of a Switch --> same result
I tried OVS instead --> same result
I tried different network vm adapters --> same result
I even tried it with different network adapters for the connected PC (Intel onboard and usb)

For configuration: It's very simple. Just stock install and I added the all the nics to vmbr0 (I also tried it with just the onboard nic connected).

Where is the problem?

I used ESXI before (no problems with network speed there), but want to switch to Proxmox because cpu idle does not work correctly and I can't use the Realtek nic on ESXI 7.
Did you tried it with virtio? Virtio is paravirtualized. All other virtual NICs are fully virtualized and way slower.
If you already used virtio you could try different driver versions. Some if them are quite buggy.


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