Connection timed out, Unknown host, Outdated client, Failed to authenticate: every message points to a specific cause, and most are fixed in minutes. This guide starts from the symptom and works back to the problem, for players and server owners alike.
Contents#
- Locating the problem in two minutes
- What each message tells you
- No response from the server
- Sleep mode, the false alarm
- DNS, the one nobody checks
- The server answers and turns you away
- The server requires a launcher
- Your friends cannot join your server
- When there is nothing to fix
- Frequently asked questions
Introduction#
You have the address, you have the game, and it will not connect. Before looking for a fix, you need to know where the problem sits: on your machine, on your connection, or on the server. Most people skip that step and spend hours changing settings that had nothing to do with it.
This guide starts from the symptom and works back to the cause. If what you need is the connection procedure for your platform, our guide on joining a Minecraft server is the one to read.
Locating the problem in two minutes#
Three tests, in this order. They fix nothing, they tell you where to look, and that is exactly what most troubleshooting attempts are missing.
Test 1: another server. Add any large public server to your list. If it responds, your game, your account and your connection all work. The problem is on the side of the server you are aiming for, and half the possible causes disappear at once.
Test 2: another network. Switch to your phone's hotspot. If it suddenly works, your router, your firewall or your internet provider is blocking something. If nothing changes, your network is in the clear.
Test 3: someone else. Ask a friend to try the same address. If they get in without trouble, the server is running and the problem is on your end.
Write down the result of all three before going further. The rest of this article assumes you know which one failed.
What each message tells you#
| Message shown | What it actually means |
|---|---|
| Connection timed out | The server never answered, nothing reached it |
| Connection refused | The machine answers, but nothing is listening on that port |
| Unknown host | The address was never even translated, no connection was attempted |
| Outdated client / server | The connection succeeded, it is the protocol that differs |
| Failed to authenticate | The server reached you, it is Microsoft that did not validate |
| You are not whitelisted | Everything works, this is a deliberate refusal by the owner |
| Server is starting, please reconnect | The server was waking from sleep, nothing is broken |
The key distinction is right there. The first three mean the connection never completed. The next four mean it completed and was rejected. Those are not remotely the same job.
No response from the server#
Timed out, refused, red cross in the list.
If test 1 passed and test 3 passed too, the server is running and your network is blocking. Look at the firewall first: allow Java and Minecraft rather than switching protection off. Then the type of network. A corporate, campus or hotel network almost always filters the port Minecraft uses, and there is nothing you can do about it from your machine.
If test 3 failed as well, nobody is getting in. The server is stopped, under maintenance, or closed for good. Its listing on a server directory or its Discord will confirm that in seconds.
If the message says the connection was refused rather than timed out, that is valuable: the machine exists and answers, but the port is closed or the server is listening elsewhere. On a public server, that almost always means it is switched off.
Sleep mode, the false alarm#
Here is a cause that appears in no guide and wastes a considerable amount of time.
Most hosts put the server to sleep when it stays empty for a few minutes. Your first connection attempt fails, sometimes with a message asking you to reconnect, and it is that very message which starts the machine in the background.
Wait thirty seconds and try again. If the second attempt works, there was never a problem: you were simply the first player of the day. This is common on small community servers, and a player who gives up after the first failure wrongly concludes the server is dead.
DNS, the one nobody checks#
Typical situation: everything worked, nothing works any more, and you changed nothing. Your friends connect without trouble. You get an unknown host or a timeout.
The culprit is often your internet provider's DNS, which no longer translates the server's domain name correctly. It can happen after a system update, a change at the provider, or for no identifiable reason. It is a case documented for years on French forums, and it is almost always diagnosed last, after full reinstalls of Java and the game that served no purpose.
The test is immediate. If the server also publishes a numeric address, try it. If the IP gets through while the domain name fails, you have your answer: switch your connection's DNS to Cloudflare's or Google's, in your Windows network settings or in your router's interface. The change is reversible and carries no risk.
The server answers and turns you away#
The connection completes then drops with a message. That is relatively good news, the address is right and the server is running. The connection guide covers the basic steps for these four cases, here is how to check when those are not enough.
Version mismatch. The message does not tell you which version the server expects. Its directory listing or its website does, and watch for the trap: some servers accept a range of versions through a compatibility plugin, others demand the exact number. If you have several profiles in your launcher, check which one is actually running, that confusion is a classic.
Authentication failure. If relaunching the launcher is not enough, run test 1. Failing on every server points to a Microsoft service outage, which happens a few times a year and resolves itself. Failing on one server while others work means that server has a problem on its side, not you.
Whitelist. This is not a fault, it is a deliberate filter. The server wants to know who comes in, usually through an application on its website or Discord. Persisting from inside the game will get you nowhere.
Ban. The message usually says so, sometimes with a reason and a duration. The only route is the server's unban procedure.
The server requires a launcher#
If no address works on a large modded French server, that is probably normal. These servers run through their own launcher, which installs the mods and handles the connection. There is nothing to type into the multiplayer menu, and the IPs you will find on third-party directories are either stale or unofficial copies.
The details on address formats and edge cases are in our guide on the Minecraft server address.
Your friends cannot join your server#
The reverse case, and by far the most frustrating: the server runs at your place, you get in, nobody else does. Seven causes, in order of checking.
You gave out your local address. The number one mistake. An address starting with 192.168 or 10.0 only works on your own network. Your friends need your public address.
The port is not forwarded. A server hosted at home requires port 25565 to be forwarded to your machine in the router interface. A port testing tool tells you in ten seconds whether it works, and saves you from guessing.
The firewall blocks Java on inbound. This is a separate step from port forwarding. Both are required, and many people only do one.
Versions differ. Your friends must run the same version as your server.
The whitelist is on. It can be on by default depending on the configuration. Add your friends or turn it off.
Online mode rejects a player. By default, the server requires an official account. A friend on a non-premium version will be turned away. Disabling that check opens your server to anyone: only do it knowingly.
Your provider does not give you a dedicated address. Some plans, particularly on recent fibre and on 4G or 5G, share one public address between several subscribers. Port forwarding then becomes impossible whatever you do. The symptom is clear: the port test fails every time even though your configuration is correct.
In that last case there are two ways out. A tunnelling service, which exposes the server without touching the router. Or a host, which settles forwarding, firewall and uptime in one go.
One owner's reflex to finish: if the server refuses to start after adding a plugin or a mod, remove it and restart before looking anywhere else. Nine start-up crashes out of ten come from the last change made. Our guide on essential plugins covers the installation method that avoids this kind of lock-up.
When there is nothing to fix#
Three situations where the problem is not yours.
The server has closed. Community servers often shut down without notice. A listing offline for weeks is fairly clear.
The server is full. Some refuse connections past a threshold, with an explicit message. Try again at a quieter hour.
Mojang services are down. Rare, and test 1 reveals it immediately.
To find out whether a server is still running before digging further, its listing on the Minecraft server ranking shows its live status and connected players.
Frequently asked questions#
How do I know whether the problem is me or the server? Try joining another public server. If it responds, your game, your account and your connection work, and the problem is on the side of the server you were aiming for. If that fails too, look at your machine or your network.
What does unknown host mean on Minecraft? The domain name could not be translated into an address, so no connection was even attempted. Either the address is mistyped or outdated, or your connection's DNS no longer resolves it. If the numeric address works while the name fails, change your DNS.
Why does the server fail on the first attempt then work on the second? That is the host's sleep mode. The server goes to sleep when empty, and your first attempt wakes it. Wait about thirty seconds and reconnect, there is nothing to fix.
My friends cannot join my server, why? In the vast majority of cases, you gave them your local address instead of your public one, or port 25565 is not forwarded on your router. Check those two before anything else.
Do I have to disable my firewall to play? No. Switch it off for a minute to identify the cause if needed, then turn it back on with Java and Minecraft added to the allowed programs. A permanently disabled firewall for the sake of a game is a bad trade.
Conclusion#
Remember the method rather than the list. Try another server, another network, another person: three tests that tell you within two minutes which side to look at, and spare you pointless reinstalls. Then read the message on screen, which always separates a connection that never completed from one that was rejected.
And keep in mind the two causes missing from every guide: sleep mode, which makes the first attempt fail without anything being broken, and DNS, which can give out overnight without you having touched a thing.
If the server stays unreachable, it may simply have closed. The Minecraft server ranking shows the live status of every server, and our guide on the different types of servers will help you pick one that matches what you are after.
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