lxc.mount.entry = /dev/net/tun dev/net/tun none bind,create=file lxc.mount.entry = /dev/ppp dev/ppp none bind,create=file
NOTE: PPP requres CAP_NET_ADMIN, and this is not possible to setup in unpriv container
Some hints:
# With this container fails #lxc.cap.keep: net_admin lxc.cgroup.devices.allow = c 108:0 rwm
# On PVE host! chown 100000:100000 /dev/ppp