We recently had to set up an L2TP tunnel for our apple devices, since the last iOS 10 update took PPTP out of the picture. It was a huge PITA too, because I didn't figure out for a while that the secondary tunnel wouldn't let me reuse existing user accounts in our Watchguard.... that was some fun trial and error. And the WG how-tos never specified anything about needing different user accounts. It sucks to do all the steps right and then get login errors... makes ya feel like an amateur.