Double NAT problem

hello
my ISP provide the router: Sagemcom F@st 3184 that provide Lan and Wireless network to part of the house.
In other part i got Asus RT-AC66U Router. the ASUS is connected directly from the ISP router.
I cant access my router from outside the network and the apps like Aicloud do not work due to "Multiple NAT" problem.
Is there any way to getthe ASUS router to see the IP provided by the ISP?
in adittion, i preffer to leave the ISP router as is and not make it as bridge.

Thanks