Maybe related, maybe not, /31 support has been added only recently in 7.18.2:
http://forum.mikrotik.com/t/v7-18-2-stable-is-released/182200/1
so its implementation has not been widely tested.
Maybe related, maybe not, /31 support has been added only recently in 7.18.2:
http://forum.mikrotik.com/t/v7-18-2-stable-is-released/182200/1
so its implementation has not been widely tested.