said by bbarrera:
Its actually L2TP over IPSec (L2TP/IPSec), with IPSec used to secure L2TP traffic.
While I have L2TP over IPSec working with the iPhone and iPad, it won't work when I use my work LAN, which is unfortunately double-NATted. It also doesn't work with the MacBook Pro at work, probably for the same reason. For the iDevices, it's easy; I switch to LTE but that doesn't cut it for the Macs. Any idea how to deal with double NATting? Or is that even an issue?