26.1.1 MTU Issues on PPPoE

[Taunt9930]

This does not look like an MTU issue if you can use those ping sizes - it look just fine.

Did you also use traffic shaping? Maybe the old ISP had lower speeds and you shape it to fit? Happened before...

Just saw that you disabled all shaping...

No idea what could be wrong.

It's a weird one, isn't it!?

When I've got more time I'll try a 3rd update from the working 25.7 snapshot.

[Boxer]

I would roll back to 25.7.11_9, delete your wan mtu and leave it blank, reboot. Then update to 26.1 and re-enter your wan mtu 1508. Maybe there's some shenanigans during the update

[ProximusAl]

I'm following this intently, as I've just ordered Zen and want to use 1508 MTU.

Please keep us updated...

[staticznld]

I am running PPPoE over VLAN 6 for KPN FTTH in the Netherlands.
When looking at my "WAN" interface, I see that my MTU is set to 1508.
Under Devices → Point-to-Point → PPPoE, no MTU is set.
Under Interfaces → Overview, IGC0 (my physical NIC) shows an MTU of 1512.

I remember that at some point I had to add the physical adapter to the interfaces and set the MTU to 1512.
Was that in version 23.7?

Current output of http://pmtud.enslaves.us/
No IPv6 connectivity to http://pmtud.enslaves.us/ ! (tested at 2 locations)
Yesterday IPv6 MTU was looking ok!

Code Select Expand

Direction    Tested Maximum Size Segment    Client Sent MSS    Notes
Server to Client IPv4    1460    1460    OK
Client to Server IPv4    unlimited    (n/a)    OK
got in probe for mss 536 (max seg 1460)
got in probe for mss 1460 (max seg 1460)
got in probe for mss 1460 (max seg 1460)
finished in probing, maximum mss 1460 peer mss 1460 initial peer mss 1460
got out probe for mss 371
got out probe for mss 1461
got out probe for mss 9000
finished out probing, maximum mss 9000

[Taunt9930]

I would roll back to 25.7.11_9, delete your wan mtu and leave it blank, reboot. Then update to 26.1 and re-enter your wan mtu 1508. Maybe there's some shenanigans during the update

That's not a bad idea. It's possible I've already tried that, but I'll re-visit later when the house is empty.

[Enverex]

I'm seeing the same issue. I found this thread before upgrading so I blanked all the MTU boxes prior to upgrading, but putting 1508 back into the PPPoE adapter post upgrade also results in breaking a lot of the internet as other people here mentioned. I've had to go back to blank/default for now which isn't ideal.

[hakuna]

Oh wow, so this could be the reason of my problems.

I am trying to setup dual-stack at home and right now I have WAN > DHCP
To cut it short, my ISP wants me back to PPPoE for the WAN > DHCPv6 to receive the reservation.

I spent ages today trying to get PPPoE to work but nothing happens, in previous releases was type username, password, save, and connected.
I checked old backup configs, the PPPoE section is exactly the same but nope.

I am stuck with WAN > DHCP now and without IPV6 which only works via PPPoE for my ISP.