Product Selection

https://community.netgear.com/t5/Orbi/Find-Your-Orbi-With-the-NEW-Orbi-Product-Selector/m-p/1907267/highlight/true#M91216
https://www.netgear.com/orbi/default.aspx
https://www.netgear.com/orbi/wifi-systems.aspx
https://kb.netgear.com/000038220/What-are-the-hardware-specifications-of-the-available-Orbi-WiFi-Systems

Modem Combo Units: https://community.netgear.com/t5/Cable-Modems-Routers/What-s-the-Difference-Between-a-Cable-Modem-and-Cable-Modem/m-p/1864698#M21950
https://kb.netgear.com/000036375/What-s-the-latest-firmware-version-of-my-NETGEAR-cable-modem-or-modem-router
This would be a double NAT (two router) condition which isn't recommended. https://kb.netgear.com/30186/What-is-Double-NAT
https://kb.netgear.com/30187/How-to-fix-issues-with-Double-NAT
Couple of options,
1. Configure the modem for transparent bridge or modem only mode. Then use the Orbi router in router mode. You'll need to contact the ISP for help and information in regards to the modem being bridged correctly.
2. If you can't bridge the modem, disable ALL wifi radios on the modem, configure the modems DMZ/ExposedHost or IP Pass-Through for the IP address the Orbi router gets from the modem. Then you can use the Orbi router in Router mode.
3. Or disable all wifi radios on the modem and connect the Orbi router to the modem, configure AP mode on the Orbi router. https://kb.netgear.com/31218/How-do-I-configure-my-Orbi-router-to-act-as-an-access-point and https://www.youtube.com/watch?v=H7LOcJ8GdDo&app=desktop

What is the Mfr and model# of the Internet Service Providers modem/ONT the NG router is connected too?

https://kb.netgear.com/000051205/What-is-Ethernet-backhaul-and-how-do-I-set-it-up-on-my-Orbi-WiFi-System

What is the size of your home? Sq Ft?