Re: IPv4 specific issue with USB tethering between my Debian laptop and my phone
Vincent Lefevre wrote:
> On 2021-12-15 06:09:12 +0000, Tim Woodall wrote:
> > On Tue, 14 Dec 2021, Dan Ritter wrote:
> >
> > > Vincent Lefevre wrote:
> > > > I don't have any issue with the mobile hotspot (thus wifi between the
> > > > laptop and the phone) or with a Cosmo under Android 9 (instead of the
> > > > Samsung Galaxy Note10+), but in both cases, this is much slower, and
> > > > I sometimes get wifi disconnections.
> > > >
> > > > On my Debian laptop, I'm using NetworkManager (nmcli).
> > >
> > > Have you investigated the MTU? This sounds like a mismatch
> > > between what your laptop and phone are using.
> > >
> > > Diagnosis (besides looking at connection details on both sides):
> > > ping with increasingly large packet sizes. If it works at small
> > > IPv4 packet sizes and then stops, that's the problem.
>
> Indeed, this works up to
> ping -4 -s 1472 joooj.vinc17.net
> ping -6 -s 1452 joooj.vinc17.net
ip link set USBNET0 mtu 1450, or something like that. I don't
know NetworkManager's syntax for that; random googling suggests
that they at least had a historical problem with not being able
to set MTU on anything other than a pure ethernet or wifi link,
but perhaps they've solved that?
-dsr-
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