I just purchased a 3 pack X50-PoE and tried to configure it.

This is my existing setup:

I have a Netgear Orbi with 1 satellite. It acts as the router.There is no modem from ISP. The eternet cable from the ISP terminates directly on the WAN port of the router.

What I want to do:

I want to replace Netgear ( acting it's age) . Now I want to terminate the ISP's ethernet cable on Deco config it as the router.

Can I be done? I dont see any documentation for this everything shows connectivity through the modem or using deco as an AP. 

When I try to set up through the app, the app returns an error saying cannot determine internet connectivity. Is it because X50 cant be configed as a router?