Ubuntu VM on Proxmox – Virtio NIC Extremely Slow (2–3 Mbit/s)

[survee01]

Hi,


I have an Ubuntu 24.04 VM running on Proxmox with a Virtio network device. Network performance on this VM is extremely slow compared to other VMs on the same host.

Details:

• Proxmox VE 8.x
• Guest: Ubuntu 24.04 LTS
• Network: Virtio (paravirtualized)
• MTU currently 1500 (tried raising to 6000 in Proxmox GUI, didnt fix)

Download speed is ~2–3 Mbit/s, Upload: ~3 Mbit/s, ping is fine.

ethtool ens18

Settings for ens18:
        Supported ports: [  ]
        Supported link modes:   Not reported
        Supported pause frame use: No
        Supports auto-negotiation: No
        Supported FEC modes: Not reported
        Advertised link modes:  Not reported
        Advertised pause frame use: No
        Advertised auto-negotiation: No
        Advertised FEC modes: Not reported
        Speed: Unknown!
        Duplex: Unknown! (255)
        Auto-negotiation: off
        Port: Other
        PHYAD: 0
        Transceiver: internal
netlink error: Operation not permitted
        Link detected: yes

I've tried,
Restarting the network
Verified connectivity
Attempted reinstall of Virtio drivers
Checked VM hardware, NIC model is Virtio

I've looked at countless other forum posts and wasn't able to fix anything, other VMs internet speed is completely fine, it's just this VM that is having this bottlenecked performance.

 

[Stanlabs]

Hello Survee,

I looked at all of the details you have provided, of which I have the following reccomendations:
1.