MTU issue after 25.1

[henri9813]

Hello,

i have issue with the opnsense 25.1



Here is my setup:
OPNsense 25.1.6_4-amd64
FreeBSD 14.2-RELEASE-p3
OpenSSL 3.0.16
AMD EPYC 4464P 12-Core Processor (4 cores, 4 threads)
RAM: 8GB DDR4
Disk: 50GB ZFS.


My docker container got random timeout to other networks.

in tcpdump, i see incoming packet ( on the server interface ) with length higher than 1500 ( 1506 ) i don't understand why.

My router cannot send ping higher than my MTU, normal

Code Select Expand

root@gco-001-router-001:~ # ping -s 1472 -D PUBLIC_IP
PING PUBLIC_IP (PUBLIC_IP): 1472 data bytes
1480 bytes from PUBLIC_IP: icmp_seq=0 ttl=64 time=2.179 ms
1480 bytes from PUBLIC_IP: icmp_seq=1 ttl=64 time=2.302 ms
1480 bytes from PUBLIC_IP: icmp_seq=2 ttl=64 time=2.151 ms
1480 bytes from PUBLIC_IP: icmp_seq=3 ttl=64 time=2.152 ms

root@gco-001-router-001:~ # ping -s 1500 -D PUBLIC_IP
PING PUBLIC_IP(PUBLIC_IP: 1500 data bytes
ping: sendto: Message too long
ping: sendto: Message too long

However, from a computer inside the LAN.

Code Select Expand

[root@local-vm ~]# ping -s 3000 -D PUBLIC_IP
PING PUBLIC_IP (PUBLIC_IP) 3000(3028) bytes of data.
[1747332539.430593] 3008 bytes from PUBLIC_IP: icmp_seq=1 ttl=63 time=3.56 ms
[1747332540.431041] 3008 bytes from PUBLIC_IP: icmp_seq=2 ttl=63 time=2.34 ms


I also post it here https://github.com/opnsense/src/issues/235#issuecomment-2885157470

I have some difficulty to understand why i got randomly this issue.

Best regards