I am trying to create an unimpeded path MTU of 1500 on my OpenWRT router (Belkin RT-3200). I built the firmware from git Master, with kernel version 6.1, and batman-adv version 2023.2. I have a batmesh hard-if device mastering an 802.1S mesh, which are both set to MTU=2304.
Using Luci (OpenWRT web gui for uci), I set the MTU of bat0 to 1504 to accommodate .1q vlans on bat0 -- bat0.5, bat0.110, etc.
I see in the system log:
kern.err kernel: [751585.375855] bat0: mtu greater than device maximum
Also, if I do:
#> ip link set bat0 mtu 1504
I get:
ip: SIOCSIFMTU: Invalid argument
and if I test:
#> ip link show bat0
...it says that my mtu is 1500 still.
For my life I can't see anything I'm doing wrong. Why can't bat0 have MTU greater than 1500?
I don't have any other devices mastered by bat0, other than my .1s wifi mesh link.
Throwing myself at your mercy. Help?