WireGuard Windows should have default MTU of 1280.

[Roman Mamedov]

On Tue, 22 Feb 2022 00:57:10 +0500
Roman Mamedov <rm at romanrm.net> wrote:

> On Mon, 21 Feb 2022 22:16:22 +0300
> Michael Tokarev <mjt at tls.msk.ru> wrote:
> 
> > 21.02.2022 22:11, Michael Adams wrote:
> > > Throwing in my two cents: I was using MTU 1280 on Tinc a few years back, for IPv6 VPN support on Windows & Linux. It's good practice.
> > 
> > Lemme guess. The OP is routing wg packets over IPv6?  Can this be
> > the problem here, because V6 has larger overhead so that 1420 is
> > too large to fit into 1500 bytes together with IPv6 header?
> 
> 1420 is picked specifically so that it fits into a 1500 byte packet with IPv6.
> 
> If you run WG exclusively over IPv4, you can use up to 1432.

Correction: 1440.

https://www.mail-archive.com/wireguard@lists.zx2c4.com/msg01856.html

I'm just used to subtracting 8 everywhere, because my ISP *does* use PPPoE. :)

-- 
With respect,
Roman