I have a /29 routed subnet assigned by my ISP which is provided over PPPoE. I can get the ER7206 via Omada to connect when using PPPoE and not specifying the secondary connection - from a quick chat with my ISP that would only be needed if I were to have a separate transit subnet which they don't provide. 

The IPs in the 82.68.xxx.72/29 subnet are routed to the IP which is assigned to the router 82.68.xxx.78 making the addresses 82.68.xxx.73-77 assignable to devices on the network.

I've created a LAN wired network with the IP as 82.68.xxx.78/29 (same as the WAN gateway) and then a DHCP pool to assign 82.68.xxx.73-77 on VLAN 1000 and a device plugged into a switch gets an IP from the pool correctly and can make outbound requests. However, I can't make inbound requests to the assigned IP.

Is this possible to do with Omada and the ER7206 or am I going to have to use something else to manage the extra public IPs and their routing.

Some Posts of what others have achieved with other vendors.

https://www.draytek.com/support/knowledge-base/4796

https://community.ui.com/questions/-29-without-a-transit-address/b498ab12-adab-40c0-b94b-6042eb2db6da