PPPoE connection issue with 24.10.3/4

[LordSpectre]

Dear community,
I’m experiencing an issue with updating OpenWRT running as a VM under Proxmox. Currently, I’m using version 24.10.2 (openwrt-24.10.2-x86-64-generic-ext4-combined.img), which works perfectly (previously I had 24.10.1, which also worked flawlessly). It successfully establishes a PPPoE connection via eth3/eth3.835@eth3.

The problem is that if I update to version 24.10.3 or 24.10.4, OpenWRT can no longer establish the PPPoE connection (eveything else work as expected anyway).

So, after upgrading my OpenWrt VM from 24.10.2 to 24.10.3 or 24.10.4, PPPoE completely stopped working. pppd loads normally and sends PADI packets, but never receives any PADO responses, it just times out with

Timeout waiting for PADO packets  
Unable to complete PPPoE Discovery phase 1

The same configuration works perfectly if I restore a backup running OpenWrt 24.10.2, so it’s probably a software or driver regression introduced in the newer builds.

Setup details:

• OpenWrt running as a VM on Proxmox

• Intel X710 / i40e NIC passed through via VFIO to the VM

• PPPoE over VLAN 835

• Tested both kernel 6.6.109 and 6.6.110, same result

• Disabling software/hardware flow offload, changing MTUs, and turning off GRO/TSO didn’t help

• tcpdump confirms that PADI packets are transmitted on eth3.835, but no PADO ever comes back

If I downgrade back to OpenWrt 24.10.2 (same VM, same config, same hardware), PPPoE connects instantly.

Looks like a regression in the i40e driver or pppd 2.5.1 handling VLAN-tagged PPPoE traffic, possibly related to VLAN offload or checksum offload changes in kernel 6.6.x.

Has anyone else experienced PPPoE discovery failures with Intel i40e NICs on recent OpenWrt builds?
Thank you
Lucas

[brada4]

@LordSpectre

passed through via VFIO

You have to attach VF to VLAN outside VM as per intel ldocumentation.

There is no problem with vlan or pado or netcard, just configuration before RTFM

[LordSpectre]

EDIT:

Even though your reply wasn’t exactly kind, thank you for pointing it out. I moved VLAN 835 to Proxmox and passed the VF to the OpenWRT VM. Now release 24.10.4 works perfectly as well. I hadn’t noticed the relevant part in the “FM”.