Hosting a Game Server Over IPv6: Does It Get Around CGNAT?

Hosting over IPv6 can get around CGNAT, because IPv6 gives each device its own public address with no NAT in the way. You open the game's port for your server PC in the router's IPv6 firewall (not port forwarding), and friends connect to the PC's global IPv6 address. It only works when the game server listens on IPv6, your ISP lets inbound IPv6 through, and every player also has working IPv6, which in practice limits it to small groups.

Why IPv6 changes the picture

IPv4 addresses ran out, which is why ISPs share them with NAT and carrier grade NAT. IPv6 has enough addresses for every device, so your ISP gives your home a whole block (a prefix, often a /56 or /64) and each device gets a public address from it.

No NAT means no port forwarding. Instead, your router's IPv6 firewall blocks unsolicited inbound connections by default, and you add a rule to allow the game port to one device. Behind CGNAT, where IPv4 forwarding is impossible, this can be the only direct route in. See how to tell if you are behind CGNAT if you are not sure.

Check 1: do you have IPv6

On the server PC:

Windows: run ipconfig and look for an IPv6 Address that starts with 2 or 3 (for example 2601:... or 2a02:...). Ignore addresses starting with fe80; those are link local and only work on your LAN. Windows also shows a Temporary IPv6 Address, which changes over time.
Linux: ip -6 addr show scope global

Then visit an IPv6 test site such as test-ipv6.com from the same PC. It should show a score above zero for IPv6.

Your friends need to do the same check. If they do not have IPv6, they cannot connect to an IPv6 only address. This is the biggest limit of the whole approach.

Check 2: does the game support it

Game	IPv6 support
Minecraft: Java Edition	Yes. Leave `server-ip=` blank in `server.properties` and the server listens on IPv4 and IPv6.
Minecraft: Bedrock Edition	Yes. `server.properties` has `server-portv6` (default 19133).
Most Steam dedicated servers (Valheim, Palworld, ARK, Rust)	Usually IPv4 only, or no way to type an IPv6 address in the join box.

If the game client has no way to enter an IPv6 address (or the server browser only lists IPv4), IPv6 hosting will not work for that game regardless of your network.

Step 1: use the stable address

Windows uses temporary IPv6 addresses for outgoing connections and rotates them. Your server should be reached on the stable one:

In ipconfig, use the line labelled IPv6 Address, not Temporary IPv6 Address.
On Linux, the address without the temporary flag in ip -6 addr.

Some routers let you reserve an IPv6 address or set a static interface ID. If your prefix changes (common on some ISPs after a reboot), the address changes anyway, which is where DDNS comes in.

Step 2: open the port in the router's IPv6 firewall

Router menus call this different things:

Google Nest Wifi: Port management, IPv6 tab ("port opening"). See Nest Wifi port forwarding.
eero: Reservations & port forwarding, IPv6 Firewall Rules. See eero port forwarding.
ASUS: Firewall, IPv6 Firewall tab.
Netgear: varies by model; some have no inbound IPv6 rules and allow or block everything.
Xfinity, Spectrum, Starlink router: limited or no IPv6 inbound controls. With some ISP gateways you cannot open IPv6 ports at all.

Add a rule allowing the game's port and protocol to the server PC's IPv6 address. Then allow it in the PC's own firewall too. Windows treats IPv4 and IPv6 the same way under one rule, so the rule from Windows Firewall rules for a game server covers both.

Step 3: give friends the address

IPv6 addresses contain colons, which clash with the address:port format. Most games use square brackets:

[2601:db8:1234:5678::25]:25565

Minecraft Java accepts that format in the Direct Connect box. If the port is the default, the address alone works.

A hostname is far easier to share. Point a DDNS name with an AAAA record at your server's IPv6 address. Many DDNS services and router clients support AAAA records; see dynamic IP and DDNS for a home game server.

Step 4: test from an IPv6 network

Mobile data is often IPv6 enabled, which makes a phone hotspot a handy test network. Connect a laptop to the hotspot, check it has IPv6 at test-ipv6.com, then join the server.

Where it falls apart

Friends without IPv6. Plenty of ISPs and many corporate, school and older networks still do not provide it. Those players simply cannot connect.
ISPs that block inbound IPv6. Some mobile and fixed wireless providers filter unsolicited inbound IPv6 even though they give you an address. Check your situation on 5G home internet and Starlink.
Changing prefixes. Some ISPs rotate the prefix on reconnect, which changes every device's address.
Games without IPv6. Most Steam based survival servers fall into this group.

Dual stack is the goal

If your ISP gives you both a public IPv4 and IPv6, use normal IPv4 port forwarding for everyone, and IPv6 is a bonus. IPv6 hosting is a workaround for the CGNAT case, not a replacement.

Gameplay from Minecraft: Java Edition

Or skip addressing entirely

A hosted server has a public IPv4 address that every player can reach, whatever their ISP. GamezServers servers come with their own address and open ports, so the IPv6 question never comes up. Look at Minecraft server hosting or the full games list.

FAQ

Can I host a Minecraft server on IPv6 only?

Yes. Java and Bedrock both support IPv6, but only players with IPv6 can join.

Do I need to port forward on IPv6?

No forwarding, but you usually need to open the port in the router's IPv6 firewall, plus the PC's firewall.

Why does my IPv6 address keep changing?

Windows rotates temporary addresses, and some ISPs change your prefix after reconnects. Use the stable address and a DDNS AAAA record.

Is hosting on IPv6 less safe?

Not inherently. Your device is reachable only on ports you open, the same as IPv4 forwarding.