Config tuning after server move.

[meyergru]

There is nothing that is "computed".

The mtu.sh script will tell you what really gets through in the upmost layer. That is what you can set the MTU of the upmost layer (=WAN) to.

What actually can get through, though, depends on what the lower layers can accomplish. This is dependent on what the hardware can do, but also limited by what MTU you set there. Also, each layer deduct from its predecessors, because the packets payload is augmented by the overhead of the lower layers, like VLAN and PPPoE.

Thus, if you want 1500 MTU on the WAN layer (and you do!), you must have more than that on the the PPPoE and VLAN layers, respectively. Normally, to have 1500 bytes MTU as a payload on the WAN layer, you need to have 1512 MTU on the physical layer (which is ethernet and usually has a default MTU of 1500), such that VLAN header, PPPoE header and 1500 bytes of payload will fit in. Thus, you will have to set MTUs for every single layer like I depicted (even with the unexpected idosyncrasies included) in my instructions. Each layer adds another few bytes of overhead to the payload.

IDK what works in your specific case, you will have to find out for yourself and test the result with mtu.sh.

P.S.: Obviously, this calls for a HowTo.

[TomT]

I've updated my MTU and restarted my server.
So far things are looking ok.

Thanks for your help and advise and the How To.