[Warning: DMARC Fail Email] Re: ipv6 connexion fail - ipv4 OK

Mike O'Connor mike at pineview.net
Fri Aug 27 21:54:16 UTC 2021

root at gw:~# ping -M do -s 1472
PING ( 1472(1500) bytes of data.
1480 bytes from icmp_seq=1 ttl=60 time=7.93 ms

Link can transmit a max of 1500 bytes as seen above.

Pinging a LAN segment has the same limit. ie PC to PC has the same result.


On 28/8/21 7:14 am, Roman Mamedov wrote:
> On Sat, 28 Aug 2021 07:05:45 +0930
> Mike O'Connor <mike at pineview.net> wrote:
>> On a 1500 link I'm having to use 1280 to get ipv6 to successfully go
>> over a wireguard link.
> Then it is not a true 1500 MTU link, something in-between drops packets at a
> lower bar. Or maybe not all of them, but just UDP, for example.
> But yeah, 1280 is worth trying as well, maybe Daniel has a similar issue.
> As for me I am using MTU 1412 WG over IPv6 on a 1492 MTU underlying link just
> fine.
>> I really think wireguard should be able to fragment and send via
>> multiply UDP packets.
> It is able to, as long as the underlying link MTU is set to a correct value
> (i.e. where largest-sized packets actually go through, and not get silently
> dropped).

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