-# Make the MTU change persistent between reboots
-sed -i '/ifconfig lxdbr0 mtu/d' /etc/rc.local
-sed -i "$ i ifconfig lxdbr0 mtu $DEFAULT_MTU" /etc/rc.local
+# Setting the MTU in the default profile will be applied to every lxc container.
+# Existing containers will need to be restarted for the new MTU to take effect.
+# This will also persist the MTU change for the host's lxdbr0
+lxc profile device set default eth0 mtu $DEFAULT_MTU