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Guide · Hytale

Hytale failed to connect to server: causes and fixes

How to fix the failed to connect to server and server failed to boot errors in Hytale: version, UDP port 5520, authentication, mods and Java.

Updated: 24 Oct 2026

The «Failed to connect to server» error in Hytale means your game couldn’t establish a connection with the server. That could be a friend’s world, a dedicated server or even your own single-player world, which also runs as a local server. The most common causes, in this order, are: the server is off or you typed the address or port wrong, your version doesn’t match the server’s, your firewall is blocking port UDP 5520, the server isn’t authenticated, or a mod is breaking startup. If the message is «Server failed to boot», the problem is on the server, not your connection.

1. Check that the server is running and the address is correct

  • Confirm with the admin or in your provider’s panel that the server is up. Newly created servers sometimes don’t accept connections at first; restart the server and the game.
  • Type the address with the port: IP:5520 or whatever port your provider gave you. Forgetting the port is one of the most common mistakes.
  • If you join with an invite code, ask for a new one: codes expire.
  • Fully close the game and the launcher and open them again. Early Access has temporary glitches that this fixes.

2. Use the same version as the server

The official server manual is clear: the client and server must have exactly the same protocol version. When an update comes out, players who already have it can’t join a server that hasn’t been updated, and vice versa.

  • Update the game from the launcher.
  • If you run the server, update it right away. Since Update 2 you can do it with /update check and /update apply --confirm.
  • Check the game branch (patchline). If your launcher is on pre-release and the server is on the stable version, or the other way around, you won’t connect.

3. Firewall and ports: UDP 5520, not TCP

Hytale uses the QUIC protocol over UDP. The server’s default port is 5520. Many guides tell you to open a TCP port or copy the Minecraft port, and that won’t work.

  • On your router, forward UDP port 5520 to the machine running the server.
  • On Windows, allow inbound traffic on that port. The official manual suggests this in PowerShell: New-NetFirewallRule -DisplayName "Hytale Server" -Direction Inbound -Protocol UDP -LocalPort 5520 -Action Allow
  • On Linux with ufw: sudo ufw allow 5520/udp.
  • If you use a different port with --bind, open that one instead of 5520.
  • To test, briefly disable your antivirus. If that fixes it, add an exception for Hytale instead of leaving it off.

If the problem happens when joining a friend’s world with a code, the cause is usually UPnP or CG-NAT. We explain it in how to play with friends in Hytale.

4. Server and account authentication

Dedicated servers must sign in with a Hytale account to validate players. If the console shows «Server starting unauthenticated» or a token error, the server will reject connections.

  1. In the server console, type /auth login device.
  2. Open https://accounts.hytale.com/device, sign in and enter the code.
  3. Check the result with /auth status.

Providers also recommend /auth persistence Encrypted so the session survives restarts. Each license can authenticate up to 500 servers. If a server stays off for more than 30 days, you’ll have to authenticate it again.

On your PC, turn on automatic time sync. A January 2026 patch fixed «invalid token» errors caused by an out-of-sync clock, and a wrong time still causes authentication problems.

5. Network drivers (slow connection or world won’t load)

Official support has an article for one specific case: single-player runs fine, but when you join a server the world doesn’t load or is extremely slow. The cause is some Intel and Realtek network drivers on Windows that don’t play well with QUIC. The fixes, from least to most invasive, are:

  1. In your network adapter’s advanced properties, disable Priority & VLAN.
  2. Disable Recv. Segment Coalescing (IPv4) and (IPv6).
  3. Disable power-saving options such as Advanced EEE or Green Ethernet.

To confirm the diagnosis, support suggests trying a USB Ethernet adapter. Write down the original values before changing anything.

6. Incompatible mods

After an update, a mod made for the previous version can stop the server from starting or keep you from joining. Remove all mods from the mods/ folder, check whether you can connect, then add them back one at a time until you find the culprit. Always download the mod version that matches your game version. If in doubt, go over how to install mods in Hytale.

7. «Server failed to boot»: Java, memory and server files

This message means the server never managed to start.

On a dedicated server

  • Java 25: it’s the version the official server requires. Check it with java -version.
  • Assets: start it with java -jar HytaleServer.jar --assets Assets.zip and make sure the path to Assets.zip is correct.
  • Memory: the official minimum is 4 GB. Set memory with -Xmx and limit view distance. The manual recommends a maximum of 12 chunks, because it’s what eats the most RAM.
  • Port in use: if another program is using 5520, start with --bind and a different port.
  • Configuration: a config.json with formatting errors prevents startup. Always edit it with the server off.

In your single-player world

Several users have fixed the error on Windows by deleting a Java environment variable (usually _JAVA_OPTIONS) left behind by another program. You can check it in System Properties > Environment Variables. If the problem started when you installed a mod, remove it. If it only happens with one specific world, try creating a new one to rule out a corrupted world.

If none of this works, open the launcher, go to settings (gear icon) and choose Open Directory > User Data > Logs. On Windows the logs are in %APPDATA%\Hytale\UserData\Logs. The game only keeps the last 10, so copy the log right after the error and attach it when you ask official support for help.

Frequently asked questions

What port does Hytale use?

By default the server uses port 5520 over UDP. You don’t need to open TCP.

Why can’t I join a server after updating the game?

Because the server hasn’t been updated yet. The client and server must be on the same version. Wait for the admin to update it or, if it’s yours, use /update.

Why do I get «failed to connect to server» in my own world?

Because single-player worlds also run on a local server. Restart the game, make sure your antivirus or firewall isn’t blocking Hytale, and check whether a recent mod is to blame.

Does changing DNS or using a VPN fix it?

Sometimes, but it isn’t an official fix. Try the steps in this guide first. If you use a VPN, turn it off to rule out that it’s what’s cutting the connection.

My friend can join and I can’t. What should I do?

Look at what’s different on your machine: the game version, firewall, antivirus or network driver. The Intel and Realtek driver issue only affects some Windows PCs.