Direct answer

Unknown Host means the client could not resolve the hostname to an address. Test the server with its numeric IP. If the IP works but the domain does not, the Minecraft server itself is usually fine and the problem is DNS or the name you entered.

Check for a simple address mistake

  • Remove https:// or http://; Minecraft expects a host name, not a web URL.
  • Check spelling and accidental spaces.
  • If you use a non-default port, use host:port unless you deliberately configured an SRV record.

Compare domain and numeric IP

If direct IP works, check the DNS A/AAAA records and wait for DNS changes to propagate. If the server’s public IP changed, update the DNS record. An incorrect AAAA record can also send IPv6-capable clients to an address where no Minecraft server is reachable.

If only one player gets Unknown Host

That strongly suggests a resolver/cache problem on that player’s network rather than a dead server. Try the numeric IP, another network, and a DNS cache refresh. If no failed join appears in the server log, the client never reached the Minecraft process.

Keep DNS separate from port forwarding

A domain only points players toward an address. It does not open the port or replace router/firewall configuration. After DNS resolves, the destination still needs a reachable Minecraft port.

Official references

These references were checked while preparing this fix. Version-specific behavior can change, so use the project documentation for your exact release when a detail differs.

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