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Does Xfinity give you a public IP? (CGNAT, static IP and port forwarding)

Short answer: Yes, as far as customers report. Xfinity home internet lines get a normal public IPv4 address, assigned dynamically, so there's no CGNAT to opt out of. A static IP is business-only, Xfinity blocks port 25 both ways, and its acceptable use policy bans public servers on home plans.

Does Xfinity use CGNAT?

Customer reports say no: residential wireline service gets a public (dynamic) IPv4 address over DHCP. We haven't found an official Xfinity statement either way, so this is low confidence. If your router's WAN IP doesn't match your public IP, check whether a second router or the Xfinity gateway is doing NAT in front of yours (double NAT), which bridge mode on the gateway usually fixes. The cited thread is on the Xfinity ISP page.

Can you get a static IP?

Not on a home plan. Xfinity staff on Xfinity's own forum say residential accounts can't get a static IP and an Xfinity Business account is needed. We haven't found a published business price yet; see static IP prices by ISP. A dynamic public IPv4 still takes port forwarding; it just can change from time to time.

Ports and terms

• Port 25 (mail): blocked in both directions, on IPv4 and IPv6, per Xfinity's own blocked-ports list. A home mail server won't receive mail directly. See home mail server behind CGNAT.
• Ports 80 and 443 (web): not on Xfinity's published blocked-ports list.
• Terms: the residential acceptable use policy bans running servers that "provide network content or any other services to anyone outside of your Premises local area network", naming email, web hosting, file sharing and proxy servers. Reaching your own devices from outside is a different case from serving the public; read the policy for your use.

What about IPv6?

Xfinity offers residential IPv6, assigned dynamically; fixed prefixes are business-only, per answers on Xfinity's forum. The checker shows whether IPv6 works on your line.

How to confirm on your line

1. Follow how to tell if you're behind CGNAT: compare the router's WAN IP with your public IP.
2. Forward a port and run the checker's port test. Its report sums up what you can host.

More detail and sources: Does Xfinity use CGNAT? · Can I self-host on Xfinity?

This site sticks to ISP facts. It doesn't review or recommend third-party products or services. Based partly on customer reports; policies change.