Updated 2026-10-27 · All guides

Can't connect to your Minecraft server? Here's how to fix it

The error message Minecraft shows tells you a lot about where the problem is. This guide goes through the common ones. Before you start, check three quick things:

1. Is the server actually running? Its console should say Done and not show a crash.
2. Can you join it yourself using localhost on the same PC? If you can't, the problem is the server, not the network.
3. Is everyone on the same Minecraft version as the server? The version is shown in the multiplayer list.

Which address should people use?

A lot of connection problems are just the wrong address. It depends on where the player is:

If the server uses a port other than 25565, add it to the end: 192.168.1.100:25570. If you try to join with your own public IP from inside your house, it may fail even when everything is set up correctly, because many routers don't support "hairpin" connections. Use localhost yourself and test the public address with a friend or your phone on mobile data instead.

"Connection timed out: no further information"

The player's game sent a request and nothing came back. Something between them and the server is silently dropping the connection. In order of how often it's the cause:

1. Windows Firewall is blocking Java. Open "Allow an app through Windows Firewall", find every entry called Java(TM) Platform SE binary or OpenJDK Platform binary, and tick both Private and Public. If there's no entry, add a rule for TCP port 25565. Third-party antivirus programs (Norton, McAfee, Avast, Bitdefender) have their own firewalls that need the same rule.
2. The port forward is missing or points at the wrong PC. Your PC's local IP can change after a restart. Check ipconfig again, and give your PC a fixed address (DHCP reservation) in the router. The port forwarding guide has steps for each router brand.
3. Your provider uses CGNAT. If the WAN address on your router's status page doesn't match the IP websites say you have, or it starts with 100.64 to 100.127, you share a public address with other customers and port forwarding can't work. See hosting without port forwarding.
4. Wrong address. Double-check the numbers and the port.

An online port checker, such as HostCraft's "Test from the internet" button or a site like mcsrvstat.us, tells you whether the server is reachable from outside, which separates firewall and router problems from problems on your friend's side.

"Connection refused: no further information"

The request reached a computer, but nothing on it was listening on that port. That usually means:

• the server isn't running, or has crashed;
• the port is wrong, for example the server runs on 25566 but the player typed no port;
• the port forward points at a different PC on your network, which actively refuses it;
• server-ip in server.properties is set to something. It should be empty.

"Unknown host"

The address couldn't be turned into an IP. It's either a typo, or a domain name (like play.example.com) whose DNS record is missing or still updating. Try the plain IP address to confirm.

"Outdated client" or "Outdated server"

The player's Minecraft version doesn't match the server's. "Outdated client" means the player's game is older; "Outdated server" means the server is older. In the Minecraft Launcher, click Installations → New installation and pick the server's exact version. If you want players on different versions to join, Paper servers can use the ViaVersion plugin, which lets newer clients join an older server.

"Failed to verify username"

The server couldn't check the player's account with Mojang. Usually it's temporary: the player should restart their launcher, log out and in, and try again. If it happens for everyone, check that the server PC has a working internet connection and that its clock is correct, because the sign-in checks fail if the time is far off. Cracked or offline launchers always get this error on an online-mode server.

"You are not white-listed on this server!"

The whitelist is on and the player isn't on it. In the server console, type whitelist add TheirName using their exact Java Edition username. If they changed their name recently, add the new one. Players with an old name in whitelist.json are matched by account ID, so name changes don't usually break it.

"You are banned from this server"

Check banned-players.json and banned-ips.json. Use pardon TheirName or pardon-ip address in the console to remove a ban. An IP ban can catch other people sharing the same internet connection, such as siblings or a school network.

"The server is full"

Raise max-players in server.properties and restart. To let a particular operator join even when the server is full, set "bypassesPlayerLimit": true for them in ops.json while the server is stopped.

"io.netty.channel…" or "Internal Exception"

These mean the connection dropped part-way through. Common causes are an unstable Wi-Fi connection (on either side), a server so overloaded it stops responding, a mod or plugin crashing while the player joins, or a mismatch in mods between client and server on Fabric. Check the server console at the moment it happened; there's usually an error with more detail.

Errors about missing or mismatched mods (Fabric)

On a modded server, the player needs the same mods that change content (blocks, items, mobs) as the server, at matching versions. Server-only mods like Lithium don't need to be on the player's side. The easiest way to keep everyone in sync is to share a modpack or the exact list of mod files.

Friends can join, but it's very laggy for them

If it's smooth for you on localhost but laggy for friends, the limit is usually your upload speed. Each player needs roughly 0.5 to 1 Mbit/s of upload, more with a high view distance. Run a speed test and look at the upload number, and use a cable instead of Wi-Fi for the server PC if you can. If it's laggy for you too, see how to fix server lag.

Bedrock players can't join

Bedrock Edition (phones, consoles, Windows "Minecraft") can't join a Java server on its own. You need Geyser, which listens on a different port, UDP 19132, and that port needs its own firewall rule and port forward. See the crossplay guide.