Took a look at your repositories....you didn't carry the '--enable-iproute2' compile flag on the 382 code. You'll see it when you add 2.4.4 to the 380 code which has that flag. It's a pretty easy fix for the ASUS added code.
Odd. I'll have to see what this flag specifically does, because it didn't seem to affect the RT-AC86U firmware so far. Can't test the RT-AC88U, the current 382 GPL for that model is broken, causing the router to get stuck when it launches the acsd process. Asus's R&D is on a national holiday until the middle of next week, so my RT-AC88U work has to be put aside for the time being.