mtu on Linux vs MacOS

[Roman Mamedov]

On Sun, 17 Jan 2021 11:36:42 +0100
Harald Dunkel <harri at afaics.de> wrote:

> Hi folks,
> 
> I am using PPPoE to connect to my IP provider. To use wireguard on Linux I
> have to reduce the MTU in wg0.conf to 1400. Using the default 1420 a ssh
> connection tunneled through wireguard gets stuck (reproducible). An echo
> of a very long line (e.g. 4096 chars) is sufficient.
> 
> The weird part is, MTU 1420 works fine for wireguard on MacOS. How comes
> that Wireguard appears to be more stable on MacOS than on Linux?

WireGuard works just fine for me on Linux using MTU 1432 if over IPv4, and
1412 if over IPv6. The underlying PPPoE device MTU is 1492 in my case. Check
which PPPoE MTU you use in Linux vs in MacOS.

-- 
With respect,
Roman