Comment 52 for bug 1671951

@raharper could you give the systemd in this ppa a test:
https://launchpad.net/~ddstreet/+archive/ubuntu/systemd

also, you're setting the MTUBytes via .link file, but that won't work inside an lxd container as that setting only has any effect during udev processing of interface 'add' uevent, which doesn't happen inside an lxd container because 1) the interface already exists when the container boots up and 2) systemd-udev-trigger.service has no effect (unlike bare metal systems or vms) because unprivileged containers can't force uevent generation by writing to sysfs uevent nodes. Instead try adding a [Link] section to the .network file with the MTUBytes; that will get applied every time networkd starts.