Guides / Troubleshooting

Project Zomboid: Server Not Showing Up, or Players Cannot Connect

The server is running, the console says it started, and either nobody can find it in the list or everyone bounces off with a port error. Project Zomboid uses more ports than most games and they do different jobs, so the exact symptom tells you which one is missing. This guide maps each symptom to its cause and gives you the fix.

Start by naming the symptom

Three different failures get described as "my server does not work", and they have three different causes. Work out which one you have before changing anything, because the fix for one does nothing for the others.

The ports Project Zomboid actually needs

This is where most setups go wrong, because the game splits its work across three groups of ports and only the first one is widely documented:

• UDP 16261 is the server port. It handles the initial handshake and is the port players type after your IP.
• UDP 16262 upwards are the player connection ports. Each connected player is handed one, starting at 16262. A four player server needs 16262 to 16265; ten players needs 16262 to 16270. Opening 16261 alone gets you as far as greeting somebody and no further, which is exactly the port 16262 closed error.
• UDP 8766 and 8767 are the Steam ports. These are how the server registers itself with Steam. With them closed, the server runs, accepts direct connections and is completely invisible in the server browser.

That last point is the one worth remembering. Being playable and being listed are two separate things controlled by two separate sets of ports, so "my friends can join if I send them the IP but the server is not in the list" is a precise diagnosis rather than a mystery.

Fixing it when you self-host

On a home connection the traffic has to survive both your router and your operating system firewall, and a rule missing in either place produces the same symptom. Work through both:

1. Forward UDP 16261, the range 16262 to 16270, and 8766 and 8767 to the machine running the server. Create separate rules per group rather than one wide range, since some routers handle large ranges badly.
2. Point those rules at a static local address. If the server machine takes its address from DHCP, a reboot can move it and silently break every rule you wrote.
3. Add matching inbound rules in the operating system firewall. On Windows this is a separate step from the router and is skipped constantly.
4. Check that the public address you are giving people is your current one. A saved server profile pointing at a stale address behaves exactly like a closed port.

If all of that is correct and traffic still never arrives, the problem may be above you. Some providers block hosting on residential lines, and carrier grade NAT means you have no reachable public address at all no matter what you forward. Neither is something you can configure your way out of.

Steam Relay, and why it is a fallback

Project Zomboid can route connections through Steam instead of accepting them directly, which works when your router cannot be opened. It is a genuine escape hatch and worth knowing about. It is not a default, though: relayed traffic takes a longer path and comes with a bandwidth ceiling, and Zomboid synchronises a great deal of zombie and player state, so a clean direct connection is noticeably smoother. Use the relay to get a session running tonight, then fix the ports.

What a managed server removes

Every cause on this page except the last section is a consequence of running the server behind your own router. On the Flux decentralized cloud the ports are opened at deploy time, the server has its own public address that does not change when your home connection does, and there is no operating system firewall of yours in the path. There is nothing to forward, so there is nothing to forward incorrectly.

It also removes the version drift that produces the other classic Zomboid connection failure. If your players are being rejected with a file error rather than a port error, that is a different problem entirely and is covered in the guide on fixing the file mismatch error.

Checklist

1. Have someone try a direct connect using Join then Internet with your IP and port 16261. If that works, only listing is broken and 8766 and 8767 are your cause.
2. If joins fail with a 16262 error, open the player port range and not just 16261.
3. Confirm the rules exist in both the router and the operating system firewall.
4. Confirm the rules point at a static local address, and that the public address you are sharing is current.
5. If nothing arrives at all, check for carrier grade NAT or an ISP that blocks hosting before debugging further.
6. Use Steam Relay as a temporary unblock if the router is not yours to change.

Frequently asked questions

Why is my Project Zomboid server not showing in the server list?

Almost always because UDP 8766 and 8767 are closed. Those are the Steam registration ports, and without them the server cannot advertise itself even though it is running and reachable by IP.

What does "port 16262 closed" mean?

That the player connection ports were never opened. 16261 handles the handshake and each player is then given a port starting at 16262, so a server with only 16261 open fails at the moment somebody actually tries to join.

Can players join a server that is not listed?

Yes. Choose Join then Internet and enter the IP and port 16261 directly. If that works while the listing does not, you have confirmed the Steam ports are the problem.

Could my ISP be the cause?

Possibly. Some block hosting on residential connections, and carrier grade NAT leaves you without a reachable public address regardless of your forwarding rules. Neither is fixable from the router.

Deploy a Project Zomboid server with every port already open →