FreeBSD 13.0-RC1 ethertype IPv6 (0x86dd), length 2942 on 1500 MTU

[Lars Schotte]

Hey friends,

I am running this FreeBSD 13.0-RC1 and I am experiencing strange
Ethernet frame sizes, TCP sizes well above 2500 on an MTU of 1500.
Somehow it seems that this problem only applies on IPv6,
IPv4 works fine.

I have seen some strange network behaviour with TCP connections
randomly dropping under load, and now I see that they are too big.
MSS-MAX on PF also does not help. It seems to ignore my 1440 setting.

Something is broken here and I do not know what.

Is anyone else experiencing this on IPv6?

-- 
 Lars Schotte
 Mudroňova 13
92101 Piešťany