[HOWTO] Configure WAN MTU with VLAN and / or PPPoE

[hushcoden]

...there are Merans given how to Check if they work for your setup.

Could you tell me how?

[meyergru]

Via the ping commands as given in the first Post.

[AlexLeporiday]

This actually finally worked for me! UK ISP on the CityFibre network, so I need a VLAN.
I've been battling with Baby jumbo frames on OpnSense for the last day or so and was about to give up when I found this guide.

I had igc0 set to 1512. I had to add it as an interface to get the ability to change it but this was already done.
I had vlan01 set to 1508. I had to add it as an interface to get the ability to change it but this was already done.
I set PPPoE to 1500 and I could see it was still set to 1492! It was driving me mad.

Turns out I needed to set 1500 in the advanced options for the PPPoE connection it worked instantly.