Still unable to get 1500 mtu on pppoe on 23.7.5 no matter what I do. Why?

[staticznld]

Interfaces - point to point - devices edit the PPPoE tunnel under advanced no Mtu set?

My situation PPPoE over vlan6.

With 23.7.5 no additional devices configured to force an MTU of 1500 on the WAN interface.

[allebone]

Interfaces - point to point - devices edit the PPPoE tunnel under advanced no Mtu set?

Correct. Nothing set here.

[franco]

So what's your PPPoE parent device? Do you have any assigned? Do you have MTU set anywhere but the WAN interface itself?

If you want PPPoE to have 1500 the WAN interface must set 1508 and it will set all accordingly up and down the chain of devices. I'm not sure it's more complicated than that now and I fail to explain it any more simple.


Cheers,
Franco

[allebone]

So what's your PPPoE parent device? Do you have any assigned? Do you have MTU set anywhere but the WAN interface itself?

If you want PPPoE to have 1500 the WAN interface must set 1508 and it will set all accordingly up and down the chain of devices. I'm not sure it's more complicated than that now and I fail to explain it any more simple.


Cheers,
Franco

I posted the screenshots and subsequently deleted the parent dummy device as per the advice of the other poster. Nothing has helped at all. I have done exactly as you said.

[RamSense]

@allebone , @franco, I'm experiencing the same.
When I used this: https://forum.opnsense.org/index.php?topic=21207.0 and franco's patch opnsense-patch f934046cb47, I had the correct mtu 1500. Now after using OPNsense 23.7.5-amd64 it is gone...

Now I still see 1492. I deleted every MTU setting as stated here, the only place is the wan set to 1508. But I still get 1492 on pppoe.
I changed wan back to 1512, did a reboot, and still the pppoe (WAN_FTTH (wan) ) is showing 1492.

(?)

[franco]

I'm a bit exhausted from this topic and I've spent too much time on it to make numbers appearing on the screen match user expectations. I've yet to hear someone say "this fixed an operational issue I was having" so the whole thing might just be cosmetic because it's been working the former way for a decade or more.

Take that with a grain of salt. All code improvements are welcome but this is the end of it for me in a community support scope.


Cheers,
Franco

[Taunt9930]

I'm a bit exhausted from this topic and I've spent too much time on it to make numbers appearing on the screen match user expectations. I've yet to hear someone say "this fixed an operational issue I was having" so the whole thing might just be cosmetic because it's been working the former way for a decade or more.

Take that with a grain of salt. All code improvements are welcome but this is the end of it for me in a community support scope.


Cheers,
Franco

I hear you. For a glimmer of hope, 23.7.5 fixed an operational issue I was having. On previous versions if I set PPPoE WAN to 1508 (calculated 1500) and did nothing else, my WAN connection was broken. To fix it, I have to create an otherwise unnecessary/superfluous interface assignment for the parent interface (igb0) to ensure the MTU of that device was also 1508.

With 23.7.5 that is no longer necessary - setting the PPPoE WAN MTU automatically 'expands' relevant interfaces so the 'PPPoE pipe fits'. Thanks, Franco 😁

I can only assume others over time have made that many changes/fiddles/adjustments with patches and or config, that some configuration parameter has been forgotten by them, or has otherwise been left over, that is interfering.

Those still struggling - have you tried starting from clean/scratch with a basic config just to test the WAN parameter? That would surely demonstrate if it is a rogue config issue, or something else.

Have you tested if the MTU is in fact 1500, and it is just a cosmetic issue?

I have to say, random cropped screenshots out of context make your issue really hard to understand!

If it still doesn't work, I guess you should go back to the config you had that does work and move on 🤷‍♂️

[RamSense]

I did check here https://www.speedguide.net/analyzer.php?
showing 1492

MTU = 1492
MTU is optimized for PPoE DSL broadband. If not, consider raising MTU to 1500 for optimal throughput.
MSS = 1452
MSS is optimized for PPPoE DSL broadband. If not, consider raising your MTU value.

[Taunt9930]

I did check here https://www.speedguide.net/analyzer.php?
showing 1492

MTU = 1492
MTU is optimized for PPoE DSL broadband. If not, consider raising MTU to 1500 for optimal throughput.
MSS = 1452
MSS is optimized for PPPoE DSL broadband. If not, consider raising your MTU value.

If you can't work out what the config issue is, sounds like you just need to go back to the config that worked for you  ;)

[allebone]

I dont know what other screenshots are relevant. I can post any required. I did test from a client machine with do not fragment and fixed ping size, 1472 doesnt work but 1464 size does so the mtu is only 1492. I dont know what other info to give. If I did I would give it to you. I have tried what other people have tried but never can progress the issue so I am stuck. From what I can tell I do the same thing as others but it does not work for me. I use a protectli box so I would imagine its a common setup.

[annoniempjuh]

from day one wit my current ISP i have this setting:
Physical NIC: 1512
PPoE vlan: 1508
WAN: 1500

this was working until the 23.7 release. didn't change anything with it.
after upgrade to 23.7.5 and a reload of WAN, MTU is now working again at 1500, without changing any configuration.
so, for me its works fine, Thnx OPNsense Team! ;D

[staticznld]

@annoniempjuh, had the same before 23.7.5 with a working 1500mtu. For testing i deleted those dommy interfaces and set MTU on WAN 1508. After the upgrade all parent interfaces adjusted automaticly to allow 1500 MTU on PPPoE.

[RamSense]

NB: @Franco, it seems I do not get an IPv6 WAN ip anymore. The system is up and running, ipv4 and ipv6 running, only the WAN is showing ipv4 ip while DHCPv6 up, reload or release or reboot does not make any difference. setting wan mtu to my previous 1512 does not change the result. 

NB2: virtual ip's do no longer work either. So the MTU is correct, but IPv6 fails to get ip on wan, virtual IP's IPv4 and IPv6 do not work.

NB3: back with dummy interface, ipv6 is back, virtual ip's working, but MTU is at 1492. So far for my testing efforts, hope it helps.

Added NB's above after this finding: @Franco, your settings does work. WAN to 1508, deleted the dummy interface.
Than IPV6 turned red on the main OPNsense gui screen. Restarted, did assign WAN interface to igb0 and than again back to vlan pppoe and restarted ipv6 again, and it works! I don't know why I had to change it back and forth for several times to get it to work, but now it is working. Sorry for the confusing.

https://www.speedguide.net/analyzer.php?
MTU = 1500
MTU is fully optimized for broadband.
MSS = 1460
Maximum useful data in each packet = 1448, which is less than MSS because of Timestamps, or other TCP/IP options used.