Setting up Orbi WiFi Mesh with ipV6

I'm not really sure how the Orbi does this but it sounds like you're not getting a prefix delegation.  I was trying to find more info on the User Class setting pictured but unable to.  If supported, I'd suggest configuring it to request a prefix delegation of /64 if you just have a single LAN.  This may very well require going back to Netgear support for further clarification.  Once you're successful, you'll see devices on your home LAN will obtain routable IPv6 addresses all with your /64 prefix delegation.

Something else you could experiment with is turning on the LAN DHCPv6 server.  My equipment is a bit more sophisticated than what the typical home user has but in my case, DHCPv6 is how I distribute IPv6 addresses to my internal clients.

Hm, thanks for that info.  I can't figure out how to change the prefix delegation but that makes sense.  I noticed now that the section "Router's IPv6 Address On LAN" says "Not Available" - I'm guessing because I'm getting a /128 delegation.  Is that how Cox is doing the DHCP, a function of the modem, or a function of my router?

I would say from what we know so far this is more likely to be an issue of the router itself.  I use a pfSense based appliance and mine works fine.  I just needed to enable IPv6 on the WAN interface, then tell all the LAN interfaces to track the WAN.  From there, each of my LAN interfaces will have the option to assign IP's via DHCPv6 using the Cox provided PD.

But because it works for me and others, I'm thinking this is more of an issue with the Orbi setup.  If you haven't checked for router updates recently that might be a good start.

If you're feeling adventurous and have a spare PC with at least 2 network interfaces, you could download a community version of pfSense and test it out.

Well, I'm not feeling that adventurous, I just want to have IPv6.  I guess it may not be an option for me at this point, both Cox and Netgear only have community support unless you want to pay for it which is ridiculous, and I'm not going to pay an extra $15/month to get Cox's wifi.

If doing IT stuff isn't something you consider to be an enjoyable activity I completely understand.

I would also suggest reaching out on the Netgear forums as those that participate there are far more likely to understand specific details regarding how to configure your particular router.  While I wouldn't necessary say go buy another router just to test but if you can get a hold of another router with IPv6 support that is also worth a try.