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

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survee01

New Member
Sep 23, 2025
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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.

Bash: 
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.
 
Hello Survee,

I looked at all of the details you have provided, of which I have the following reccomendations:
1.
 
More information regarding my setup, I've been troubleshooting for the past hour and haven't been successful. If I could get any help, that would be very much appreciated.

Bash: 
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host noprefixroute
       valid_lft forever preferred_lft forever
2: ens18: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether bc:24:11:93:5f:48 brd ff:ff:ff:ff:ff:ff
    altname enp0s18
    inet 192.168.1.25/24 metric 100 brd 192.168.1.255 scope global dynamic ens18
       valid_lft 85753sec preferred_lft 85753sec
    inet6 fe80::be24:11ff:fe93:5f48/64 scope link
       valid_lft forever preferred_lft forever
3: tailscale0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1280 qdisc fq_codel state UNKNOWN group default qlen 500
    link/none
    inet6 fe80::b8f1:de0c:dd23:ac56/64 scope link stable-privacy
       valid_lft forever preferred_lft forever
4: br-5849afa13a18: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default
    link/ether 72:ec:9d:c9:a0:79 brd ff:ff:ff:ff:ff:ff
    inet 172.20.0.1/16 brd 172.20.255.255 scope global br-5849afa13a18
       valid_lft forever preferred_lft forever
5: br-f6cd2cf2ee35: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default
    link/ether f2:4a:b3:88:62:f7 brd ff:ff:ff:ff:ff:ff
    inet 172.21.0.1/16 brd 172.21.255.255 scope global br-f6cd2cf2ee35
       valid_lft forever preferred_lft forever
    inet6 fe80::f04a:b3ff:fe88:62f7/64 scope link
       valid_lft forever preferred_lft forever
6: docker0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default
    link/ether 26:0d:28:8b:88:2b brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
       valid_lft forever preferred_lft forever
    inet6 fe80::240d:28ff:fe8b:882b/64 scope link
       valid_lft forever preferred_lft forever
7: vethd201d4b@if2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default
    link/ether 6a:56:20:e2:78:3c brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet6 fe80::6856:20ff:fee2:783c/64 scope link
       valid_lft forever preferred_lft forever
8: vethde1b226@if2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-f6cd2cf2ee35 state UP group default
    link/ether ea:90:11:b6:05:2a brd ff:ff:ff:ff:ff:ff link-netnsid 1
    inet6 fe80::e890:11ff:feb6:52a/64 scope link
       valid_lft forever preferred_lft forever
9: veth9ee68c1@if2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master docker0 state UP group default
    link/ether 62:7d:2a:08:fc:b2 brd ff:ff:ff:ff:ff:ff link-netnsid 2
    inet6 fe80::607d:2aff:fe08:fcb2/64 scope link
       valid_lft forever preferred_lft forever
Bash: 
boot: order=scsi0;net0
cores: 3
cpu: host
memory: 9000
meta: creation-qemu=9.2.0,ctime=1752516962
name: JayServer
net0: virtio=BC:24:11:93:5F:48,bridge=vmbr0,firewall=1
numa: 0
ostype: l26
scsi0: external-storage:100/vm-100-disk-0.qcow2,iothread=1,size=32G
scsi1: external-storage:100/vm-100-disk-1.qcow2,iothread=1,size=1000G
scsihw: virtio-scsi-single
smbios1: uuid=14603c37-907a-48b4-a099-245f4ca9cc4f
sockets: 1
vmgenid: 591b57c6-ac5f-4c02-b586-13021cdb062d
Bash: 
Retrieving speedtest.net server list...
Selecting best server based on ping...
Hosted by MassiveMesh Networks (Troy, NY) [194.13 km]: 2532.067 ms
Testing download speed................................................................................
Download: 2.26 Mbit/s
Testing upload speed......................................................................................................
Upload: 3.06 Mbit/s
Bash: 
auto lo
iface lo inet loopback

iface eno1 inet manual

auto vmbr0
iface vmbr0 inet static
        address 192.168.1.70/24
        gateway 192.168.1.1
        bridge-ports eno1
        bridge-stp off
        bridge-fd 0


source /etc/network/interfaces.d/*
Bash: 
00:12.0 Ethernet controller: Red Hat, Inc. Virtio network device
 
Last edited:
Hello Survee01,

i just want to give you a warm welcome to the wonderful world of website creation! There is a lot to learn and I would love to assist you. First,

Have you tried rebooting it isaac?

Second,

try fixing your internet

Third,

use the old website

your welcome,
website MASTER
 

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Last edited:
website MASTER said:
Hello Survee01,

i just want to give you a warm welcome to the wonderful world of website creation! There is a lot to learn and I would love to assist you. First,

Have you tried rebooting it isaac?

Second,

try fixing your internet

Third,

use the old website
Click to expand...
Yes, I have tried rebooting it, my internet is fine.
 
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