@Pat56 

Hi,

Is there another Comcast-provided router (or hub or gateway or whatever they call it) connected before the Archer C54 or is the Archer C54 directly connected to the modem or ONT and using connection type PPPoE?

The C54 router is connected directly to my own cable modem using Dynamic IP to Comcast cable. IPv4 works fine on my local network with the C54 router in place but IPv6 address info doesn't pass through the router. If I connect a PC directly to my modem both IPv4 and IPv6 work fine. But with the router in place between the modem and PC(s) I  get no IPv6 (other than local addresses generated by the PCs themselves). I do have IPv6 enabled on the router with all the proper settings (to my knowledge). IPv6 settings seem very limited on the C54. That's why  I was wondering if anyone has been able to use it with Comcast Xfinity IPv6.

  @Pat56 

Hi, is your IPv6 settings like this? If it doesn't work, you could also try changing IPv6 mode from Router to Bridge.

  @QRene 

Hi.

Yes, my IPv6 settings look exactly like that on the C54. And, unfortunately, those are all of the options there are.

I could use Passthrough mode (instead of Router mode) but my understanding is this would provide no security and should only be used to provide passthrough to an actual downstream router. If my understanding is wrong, please let me know. :) And thanks for posting the settings - I'm sure that was helpful for everyone.

  @Pat56 

Yeah, if your cable modem is just a pure cable modem, then you should not use the IPv6 Pass-Through (Bridge) mode on the C54. (generally, a pure modem only has one "LAN" port, while broadband devices with several "LAN" ports are mostly routers with built-in modem)

  @woozle 

Yes, my cable modem is just a cheap (Comcast approved) 1 Port deal with no routing or WiFi capability.  I depend on the TP-Link to do that. But I've never had this much trouble getting IPv6 to work on a home router before. Usually it just works without much effort. Comcast may have changed something that makes their service more difficult to use on 3rd party equipment. At this point I just don't know.

Configuring IPv6 settings for Comcast Xfinity on the Archer C54 router can be challenging if it lacks specific options. Ensure your router firmware is up to date, check DHCPv6 and ICMPv6 settings.

  @ElodyTurner 

I do have the latest firmware. Even so, I don't think the C54 has the options that it needs to work with Comcast/Xfinity. As you mentioned, I think it needs  DHCPv6 and ICMPv6 enabled. And as can be seen above, in the screenshots posted by QRene, the C54 has none of those options.