WAN PPPOE connection external addresses to VDOMs

I'm not sure how your ISP can deliver the 16 IPs (/28) on the same physical circuit over PPPoE including the device interface ip. If multiple devices sharing the same circuit, I've seen a case each device can establish PPPoE with the GW and getting one IP each. You should ask your ISP what is intented on their customer side.  

What I meant was if there were multiple devices w/ different username/password for each, those can be connected to the same Ethernet and PPPoE can provide an individual IP/GW to each device, like 10.10.10.30/28, 10.10.10.29/28, and so on. But I assumed you got only one username so I suggested asking your ISP about their intended set-up of the circuit. If they can deliver packets destined to 10.10.10.29 toward 10.10.10.30, that's fine. You can probably try tweaking routing or VIPping or something to make it work. But my current feeling is that's not what the ISP is intending.

Or, you can try sniffing the ppp interface (not wan1) while you're sending traffic from outside toward 10.10.10.29 or other IP, not 10.10.10.30. If you see the packets coming in, you can ignore all my comments so far.