Every l2tp subscriber disconnect from non-default VRF causes log errors like:
Dec 21 22:14:02 accel-l2tp[2921306]: l2tp1:: def_set_vrf rtnl_talk failed Dec 21 22:14:02 accel-l2tp[2921306]: l2tp1:: set vrf default failed ifindex=540456, vrf_ifindex=0