OPNsense PPPoE on Proxmox - PADI sent but no PADO received (Vodafone UK VLAN 101)

Hi all,

I'm trying to replace my TP-Link Archer GX90 router with OPNsense running as a VM on Proxmox, but I am stuck at the PPPoE discovery stage.

Setup:

ISP: Vodafone UK

ONT: Nokia GPON ONT

Current working router: TP-Link Archer GX90 (PPPoE works immediately)

Replacement: OPNsense VM running on Proxmox

Vodafone PPPoE requirements:

VLAN ID: 101

PPPoE username/password confirmed working

MTU 1480

Current OPNsense layout:

vtnet1 | VLAN 101 (vlan01) | PPPoE interface (pppoe0) | WAN

Proxmox:

net0 -> vmbr0 -> LAN net1 -> vmbr1 -> WAN

I have tested:

✅ PPPoE credentials (confirmed working on GX90)

✅ VLAN 101 configuration

✅ Recreated the PPPoE interface

✅ Removed/recreated WAN VLAN interface

✅ Checked OPNsense interface assignments

✅ Tested with UGREEN USB Ethernet adapter

✅ Tested with onboard Ethernet NIC

✅ Changed MAC address to match the GX90 WAN MAC (tested two variations)

✅ Verified Proxmox VM NIC configuration

Packet capture results:

OPNsense/Proxmox sends PPPoE discovery packets:

PPPoE PADI

but I never receive:

PPPoE PADO

The GX90 connects immediately and its logs show the full handshake:

PADI PADO PADR PADS LCP CHAP authentication success IPCP

However, OPNsense only ever gets as far as sending PADI and then times out.

Does anyone have any ideas what I may have missed? At this point I am wondering if there is something about Proxmox/VirtIO/OPNsense PPPoE handling that I have overlooked.