95% drop in download speed after router upgrade

This modem has a built in router. Have to routers on the same line can cause problems. 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

Try wired speed tests first. If you don't get good speed with wired, I would try the Orbi in one of the following configurations:

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

Wireless speeds, depending upon design and support, most AC wifi devices will max out at around 400-500mpbs on speed tests. My iphone 6sP gets around 500Mpbs thru the RBR50 with v16 loaded. It get 900Mpbs or just over with a wired PC. However I don't have a gateway modem, a cable modem only. 

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Basti_Hongkong wrote:
I still need to test wired speed to the router. I only got one network cable, other one is broken.

ISP Modem is Huawei Echolife HG8040H5

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