RBK50v2 Configuration

Your ISP Modem already has a built in router and wifi. 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

I would try option #3 first...

maybe this will help with your ISP modem

https://www.att.com/device-support/article/wireless/KM1336600/ATT/ATTIFWA40

---

Mavvie wrote:

c.) Trying to figure out how best to set up my IFWA-40 / RBK50v2 Netgear Orbi. From what I can tell, there's no bridge mode option for the IFWA-40, so I figured I'd just set the ATT router IP to 192.168.1.1, turn off DHCP, set the Orbi Router to 192.168.1.2 and set the DHCP pool to start at 192.168.1.10 (as to leave room for some static IPs, pcs, consoles, etc.) However, with that config I couldn't get the Orbi to receive internet to save my life. I could connect to it fine, the ATT router was receiving internet, but no dice.

---

This can never work.  With the Orbi in router mode, the LAN side has to be a different subnet than the WAN side. i.e. the DHCP pool cannot include any part of 192.168.1.x. That is why the Orbi is confused.

---

Mavvie wrote:

So I disabled DHCP on the Orbi, kept the same IP, and instead of running IFWA40 WAN to orbi WAN, ran the ethernet from IFWA40 WAN to ORBI LAN and just let the ATT router handle DHCP requests and have the IFWA40/ORBI run their own wifis. However...I seem to have a heck of time getting good connections to the Orbi's. ANYTHING that is connected to the Orbis, whether through ethernet or wifi, is drastically slower than connected directly to the IFWA40's wifi/ethernet. I can't seem to find out why..

---

This also cannot work.  Orbi must be connected using the WAN port.

There are two obvious solutions:

1. Reset the Orbi back to its original configuration (router mode with DHCP on) and connect the WAN (yellow) port to the ATT.
   The Orbi will get whatever IP address the ATT gives it and be happy.
   Connect everything to the Orbi.
   As FURRYe38 pointed out, this is a classic "Double NAT" situation which works fine 99.9% of the time.  There are specific applications which cannot function in this environment, such as port forwarding, VPN (into the Orbi LAN from internet), and some internet gaming. https://kb.netgear.com/30186/What-is-Double-NAT  Thousands of customers just "Plug in their new WiFi router" and never notice anything wrong.
2. If this should become a problem, then the Orbi can be put into Access Point (AP) mode and the AT&T will handle all DHCP work.

Most people would recommend disabling the ATT WiFi to avoid WiFi conflicts.  WiFi is really tolerant of interference and with no close-by neighbors and not much internet bandwidth, you may never notice a problem.