Orbi RBR50 with Singtel ONT to ONR upgrade

[BlueZombie]

Hi,

I need assistance with my Orbi RBR50.

Product Model: RBR50v2

Serial Number: 5R11955B01499

I have previously set it up with my Singtel ONT. I did the VLAN settings and everything was up and running with no issues.
Orbi VLAN setup for Singtel 

Today, we did a recontract with Singtel and they upgraded our ONT (Optical Network Terminal) to the ONR (Optical Network Router) and my Orbi is unable to get internet connection from it.

I can connect my 2 PCs directly to the router and get internet connection but for some unknown reason, my Orbi is unable to get internet connection. 
Due to this, Wifi is down. I can still use my PCs as they are wired connections directly to the ONR.

I called support earlier only to be told that my complimentary support for Orbi is over and I need to subscribe $75/year for their support. They person I spoke with was still nice enough to send me some email with some help.
MAC Spoofing 

But after reading through the steps, I feel like the person I spoke with mistook what I meant because I was advised by my ISP to use Orbi as AP instead. 
Even after switching it from Router to AP mode, I was unable to get internet on my Orbi router from my ONR.

I'm lost.

[FURRYe38]

Please do not post product serial numbers in public forums. 

If your ONT has a built in router, This would be a double NAT 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