1. You go to Zeroshell shell desktop
2. Find the interface you need to change MTU
> cd /
> find ./sys/devices -name *mtu
3. in your Zeroshell web interface, go to “Setup / Startup/Cron”
Select “Postboot” section and add this line :
echo 1464 > /sys/devices/??????/net/ETH??/mtu
After reboot verify this file containt, it must be 1464.
To be honest, I solved it a bit different: by adding ip command to post-boot script.
Something like (by memory):
ip ppp0 mtu=1464
ip ppp1 mtu=1464
PS: Naming command ip was dickhead stupid IMO, as searching for its uses on google etc is a hellish nightmare. There was nothing wrong with ifconfig to begin with, but some love making changes for the sake of changes.