Orbi Installation Issue

[DanKenne]

Having installation issues. WIth no router connected and only an ethernet cable between modem and computer (Mac) I can access internet using ISP network.  When I connect the router to the modem, the Orbi network is recognized and joined, but no internet service. Have rebooted modem and router numerous times.  There are no backup batteries in the modem. Have tried using two different ethernet cables. Totally out of ideas.

[FURRYe38]

What Firmware is currently loaded?
What is the Mfr and model# of the ISP modem the NG router is connected too? Built in router here? If so, This would be a double NAT condition which isn't recommended. https://kb.netgear.com/30186/What-is-Double-NAT
Couple of options,
1. Configure the modem for transparent bridge 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 

Be sure you power OFF The ISP modem for 30 seconds then back on. Walk thru the setup wizard on the RBR with a wired PC and web browser to help you get connected to the modem.