PPPoE over vlan MTU not honored

[staticznld]

With 23.1 and before i had an MTU of 1500 over my PPPoE connection.
With an dummy interface on the physical interface MTU set to 1512 [Vlan 4bits PPPoE 8bits].

ISP is KPN Netherlands, PPPoE over vlan6.

After the upgrade to 23.7 everything seemed to work fine, but when looking into interfaces - Overview PPPoE I saw that my MTU was 1492!

Fixed the problem to assign an interface to igb0_vlan6 and set the MTU there to 1508.

Is there anything changed why the MTU is not honored in 23.7?

[iMx]

Thank you - I have just assigned the VLAN interface, enabled it and set the MTU to 1508. 

This didn't seem to be required previously, hopefully it will fix the issue - will test tomorrow morning.

[iMx]

Unfortunately this didnt seem to fix it for me, after rebooting the machine this morning I still had to open the WAN/PPPOE interface and click 'Save', PPPoE then reconnects with 1500.

- WAN_PHYS set to 1512 (WAN_PHYS attachment)
- WAN set to 1508, with the PPPoE (WAN attachment) calculated to 1500.  As it should be.

The above used to work 'as is', I was on 22.7 before upgrading to 23.7 latest.

Then, after reading your post, I assigned the 'WAN_VLAN' and set 1508 there (WAN_VLAN attachment).  Rebooted this morning, but still came up at 1492 - open the WAN interface, click save, PPPoE reconnects, back to 1500.

[staticznld]

Not able to reboot right now, will try later today.
But when is was trying to resolve the issue i rebooted several times and the MTU stays at 1500.

[iMx]

Under:

Interfaces -> Point to point -> Devices -> Edit the PPPoE device

Then 'Show advanced options' do you have anything set under the 'Link Parameters ( vlan01 )'?

I didn't previously for things to work and still don't at the moment - as the MTU should already be set on vlan01, for the interface assignment, also the WAN/PPPoE interface where it shows 1508 calculated 1500.

[staticznld]

Nope completely empty.

[iMx]

I opened the below, in case anyone else is seeing this/unable to resolve:

https://github.com/opnsense/core/issues/6738

[zyx360]

Just to confirm, as i'm seeing the github issue closed/fixed, did this fix your problem and did youget this to work again? I'm still having issue (any ping size > 1464 is dropped) but suspect it's my config, can you confirm my settings are correct?

ethernet interface mtu: 1512
vlan interface mtu: not specified
pppoe interface: 1508

Looking on the cli i can see that the vlan interface is assisgned the mtu of 1508 automatically and the pppoe interface lists mtu 1500

Thanks,
Z