Fix PVE Network Speed

Fix Proxmox VE Network Speed stuck at 100Mb/s

Before Starting

I am using Proxmox VE 8.2.2, but the solution should work on any Proxmox VE version.

The Problem

After installing Proxmox VE, you may notice that the network speed is stuck at 100Mb/s, even though your network card is capable of 1000Mb/s.
In this blog post, we'll walk through the steps to identify the problem and fix the network speed on your PVE.

Identifying the Issue

First, let's inspect the network card information using the ethtool command.
Replace enp1s0 with the name of your network interface:

ethtool enp1s0

The output should look similar to this:

Settings for enp1s0:
        Supported ports: [ TP    MII ]
        Supported link modes:   10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
                                1000baseT/Full
        Supported pause frame use: Symmetric Receive-only
        Supports auto-negotiation: Yes
        Supported FEC modes: Not reported
        Advertised link modes:  10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
                                1000baseT/Full
        Advertised pause frame use: Symmetric Receive-only
        Advertised auto-negotiation: Yes
        Advertised FEC modes: Not reported
        Link partner advertised link modes:  10baseT/Half 10baseT/Full
                                             100baseT/Half 100baseT/Full
                                             1000baseT/Full
        Link partner advertised pause frame use: No
        Link partner advertised auto-negotiation: Yes
        Link partner advertised FEC modes: Not reported
        Speed: 100Mb/s
        Duplex: Full
        Auto-negotiation: on
        master-slave cfg: preferred slave
        master-slave status: slave
        Port: Twisted Pair
        PHYAD: 0
        Transceiver: external
        MDI-X: Unknown
        Supports Wake-on: pumbg
        Wake-on: d
        Link detected: yes

As you can see, the network card is capable of 1000Mb/s (line 5), but it's currently operating at 100Mb/s (line 21).

Fixing the Network Speed

To fix the network speed issue, you can use the ethtool command. The following command will set the network interface enp1s0 to operate at 1000Mb/s, full duplex, and disable auto-negotiation.
Replace enp1s0 with the name of your network interface:

ethtool -s enp1s0 speed 1000 duplex full autoneg off

In order to apply these changes, you may try to unplug and replug the network cable, or reboot the PVE.

Verifying the Network Speed

You can verify the network speed using the ethtool command again.
Replace enp1s0 with the name of your network interface:

ethtool enp1s0

The output should now show that the network speed is set to 1000Mb/s:

Settings for enp1s0:
        ...
        Speed: 1000Mb/s
        ...

Conclusion

By following the steps outlined in this blog post, you should be able to resolve the network speed issue in your Proxmox VE environment and get your system running at its full network capacity.