Fixing Network Issues in Proxmox After Adding an NVMe SSD

Overview

Adding an NVMe SSD to a Lenovo ThinkCentre M700 running Proxmox can change network interface names due to PCI enumeration shifts. When this happens, OPNsense (running as a Proxmox VM) may lose access to its network interfaces. This guide explains how to diagnose and fix the issue.

Step 1: Identify Network Interface Changes

Check available network interfaces on the Proxmox host

Run:

ip link show

If your primary NIC was previously enp1s0 and is now enp2s0, the system has renamed it.

Step 2: Update Proxmox Network Configuration

If the network adapter name has changed, update the Proxmox configuration.

Edit `/etc/network/interfaces`

On the pve1 node shell:

nano /etc/network/interfaces

Locate the section configuring vmbr0, which may look like this:

auto vmbr0
iface vmbr0 inet static
  address 192.168.1.2/24
  gateway 192.168.1.1
  bridge-ports enp1s0
  bridge-stp off
  bridge-fd 0

Change enp1s0 to enp2s0:

auto vmbr0
iface vmbr0 inet static
  address 192.168.1.2/24
  gateway 192.168.1.1
  bridge-ports enp2s0
  bridge-stp off
  bridge-fd 0

Save and exit (Ctrl + X, then Y, then Enter).

Restart networking

Apply the changes:

systemctl restart networking

If the issue persists, reboot Proxmox:

reboot

Step 3: Verify Network Settings in Proxmox UI

Go to Datacenter → Your Node (e.g., pve1) → Network.
Ensure vmbr0 is using enp2s0.
If the network is still down, remove and re-add the network bridge in the Proxmox UI.

Step 4: Reconfigure OPNsense Interfaces

Once Proxmox is correctly configured:

Start the OPNsense VM.
Open the console.
Select Option 1: Assign Interfaces.
Reassign LAN and WAN to the correct interfaces.
Save and exit.