US ISP IPv6 support › Comcast Xfinity
Does Xfinity support IPv6?
Yes. Comcast Xfinity Internet provides native dual-stack IPv6 alongside IPv4, and the Xfinity Gateway enables it by default.
Measured on Comcast Xfinity
Loading results of connectivity tests run on Comcast Xfinity in the United States…
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Run the full IPv6 connectivity test → It also checks dual stack, DNS, response times and large packets.
How Comcast Xfinity delivers IPv6
- The Xfinity Gateway or your own cable modem and router receives an IPv6 prefix from Comcast by DHCPv6 prefix delegation and advertises a /64 to your devices.
- Devices on the home network get IPv6 automatically through SLAAC.
Getting IPv6 on your own router
- Put the Xfinity Gateway in bridge mode, or use your own cable modem, so your router receives the connection directly.
- Set the router’s WAN IPv6 to DHCPv6 with prefix delegation. Comcast delegates a /64 by default; routers that request a larger prefix (a prefix size hint such as /60) can get one, which allows several IPv6 subnets.
- After replacing a router, power-cycle the modem so it accepts the new router’s DHCPv6 request.
If the test finds no IPv6
- If the router shows an IPv6 WAN address but devices get none, check that prefix delegation and router advertisements are enabled on the LAN side.
- Many routers ship with IPv6 switched off; turning it on is often the only change needed.
About these numbers
The measured rate is the share of connectivity tests on this site, run from Comcast Xfinity connections in the United States, in which IPv6 worked. Source: Comcast network AS7922. Tests are counted, not people, so someone who tests several times is counted several times; no IP addresses are stored. A rate below 100% usually means some customers have IPv6 switched off on their router or use a router that does not request IPv6, not that the network lacks IPv6.