Double NAT and DNS Loopback

Hi all,

i'm setting up an EdgeRouter X with two WAN connection in front ad an UDM Pro. I'm doing this setup to use the edge router to make a load balance of my connection.

I need some help with the setup of two functionality:

• In the EdgeRouter i setted up two DDNS updater, one for each WAN IP but using the hostmane generated by the DDNS i cant' access my services inside the UDM Pro network. I think i need something like NAT Loopback, but how i can make this functioning with my Double NAT setup?
• How i can bypass totally the EdgeRouter firewall (like a DMZ) to manage my port forwarding directly from my UDM Pro for both WANS and so make the EdgeRouter "invisible"?

Thanks