Some iPhone Apps not connecting to services over Orbi Mesh

[Pearly_Gates]

F/W: 2.3.1.60

Google Fiber Network to ISP

iPhone client

Orbi just purchased and AC3300 WiFi set up for the first time yesterday 7/21/19

A couple of my iPhone games will not connect to their server over the Orbi Mesh WiFi. The games work fine over the cellular data, but when I connect to the new home WiFi (replaced the native Google box's WiFi with the RBK50 (RBR50 and RBS50) Orbi Ultra-Performance mesh networking kit.

All other iPhone Apps work fine over the Orbit Mesh WiFit, just these two games: Golf Rival and World Golf Tour (WGT).

I've rebooted the iPhone, the Orbi's, etc. No joy.

Any other troubleshooting ideas or known solutions?

[FURRYe38]

What is the Mfr and model# of the ISP modem or ONT the NG router is connected too?

[Pearly_Gates]

Modem Mfr: Google
Model: “Network Box”

Not cable ISP, but Google Fiber

[FURRYe38]

There a built in router here by chance? 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