connectivity problems with Fusion (AT&T) Fiber and Netgear Orbi

[ritters]

We finally had AT&T show up yesterday to install our Fusion 1000 Mbps Fiber service, it appears to be fiber running into the house, converted to copper, into an Arris BGW210 modem. After connecting the new AT&T modem to our Netgear Orbi RBR50 router most services seem to be working (general web browsing, Netflix, etc) but oddly some are not (Mac and iOS app downloads/updates, some random sites, etc). Specifically iOS app store says "Could not download XXX at this time" and Mac app store gives an odder "404 download not found" error. I should note I can browse the app stores just fine, it's only downloads that are failing.

My prior setup was Comcast xfinity with the cable modem in bridge mode. I have not changed any settings on the Orbi router so in theory the Orbi was allowing the connections that I'm having trouble with now. Also interestingly I have no connection problems when using just the AT&T modem, using its builtin wifi. So it's specifically the combination of the Arris and Orbi that's blocking connections.

I've tried some of the suggestions for putting the AT&T Arris modem into as close to a "bridge mode" as it has, turning on IP Passthrough. That did not affect anything one way or the other unfortunately, though I'm not confident things are set correctly.

https://forums.att.com/t5/AT-T-Internet ... -p/5296974

I also remember enabling some IPv6 features on the Orbi a while back in an effort to fix some other iOS issues. I wonder if there's an IPv6 incompatibility between the Arris and the Orbi which is causing the (mostly) Apple-related connection issues. Maybe the app store connections want IPv6 addresses or something.

Has anyone had similar issues, especially with AT&T equipment? Some connections working and some not? Anyone have any ideas where to start for debugging?

Thanks for any tips!

[dane]

Generally in troubleshooting the idea is to eliminate things until you find the source of the issue. So, directly connect a computer with Ethernet to the router and see if the issue still exists. If not, add back in the Orbi and connect with Ethernet, then WiFi, and see where things break down to find the source of the issue.

[ritters]

Thanks Dane, I eventually figured out the incompatibility with the equipment.

To get the Orbi happy when connected to the AT&T modem I needed to turn on IP Passthrough on the modem. I ended up using DHCPS-Fixed mode with manual MAC address entry, the MAC address of the Orbi router. The issue was that the Orbi was set to present a different MAC address than the one printed on the bottom of the device. Once I corrected that my connection issues went away.

For anyone else referencing this to connect an Orbi (or probably any other router) make sure you disable the 2.4 GHz and 5 GHz wifi radios on the AT&T modem as well.