IPv6 on Comcast/Xfinity

OttoPylot

Comcast cable using a Motorola DOCSIS 3.1 modem (IPv4/IPv6 capable) and a Netgear AX4200 Mesh WiFi system. I’m interesting in checking out IPv6 but Xfinity won’t help me because I don’t use their equipment. The Netgear router has options for connecting via IPv6: Auto Detect, 6 to 4 Tunnel, Pass Through, Fixed, DHCP, PPoE, Auto Config, and 6rd Tunnel. Any ideas of which setting I can use to connect to the public IPv6 that Comcast supposedly has? IPv4 DHCP is enabled and will remain so.

MacLeech

OttoPylot auto detect

Donawalt

I was told by Netgear on their forums to set it to “Auto Config” not Auto Detect, or DHCP (which is what Comcast uses). It probably doesn’t matter but just in case…

OttoPylot

Thanks. I did set it to DHCP and while I received some IPv6 addresses, the test site I use said that the public IPv6 addresses were blocked because my assigned addresses started with “fe:” which indicates no public IPv6 address available.

OttoPylot

Followup - Auto Detect doesn’t give me any public IPv6 addresses either.

MacLeech

OttoPylot

what model modem?
Do you get IPv6 on a direct connection to the modem without the router?

OttoPylot

Motorola DOCSIS 3.1 (MB8600). I’ve never connected directly to the modem as I don’t have an ethernet port on my M4 MacBook Pro. I’ve accessed the Admin page on the modem but there is nothing there to configure or check as far as IPv4/IPv6 goes.

Jbob

Been awhile since I was on Xfinity and used the MB8600 modem. But don’t think there is anything to configure on the Modem for IPv6 to function. The settings are all within the router itself. And the “fe” addresses should be the IPv6 IP ranges.

OttoPylot

Jbob That’s what I thought but every time I try to test to see if I can access an IPv6 site I get the error message that says “fe” is not available for public IPv6 use. Talking to Comcast is an exercise in futility because I don’t use their equipment. And you are correct, IPv4/IPv6 is built-in in the modem so there is nothing to check or configure, regardless of what Comcast says. This is more of an academic exercise at this point in time but I would like to figure it out anyway. Thanks.

MacLeech

OttoPylot You’ll have to talk to Netgear about setting up their router for IPv6 with Comcast if auto detect or DHCP isn’t working, but the modem may not be receiving or handling IPv6 configurations properly either. Some modems have had issues like that in the past. Also the router logs should show IPv6 request activity, if it’s trying.

FE80 in IPv6 is a self-assigned link local addresses, kinda like the 169. IPs in IPv4.

Being able to connect direct to the modem with a computer could tell you if it’s your router config, or something else. A cheap USB ethernet adapter can be had for $10.

OttoPylot

Thanks. I’ll look around for USB to ethernet adapter and see what I can find out, but I’m not sure what to look for.