1. Verify the Server Is Running
- Look for
Donein the server console - Make sure you can join locally with
localhost
2. Double-Check the IP and Port
- Local network: use the server PC local IP (192.168.x.x)
- External players: use your public IP
- If you changed ports, connect with
ip:port(example:203.0.113.10:25566)
3. Check Firewall Rules
Allow Java and port 25565 through your firewall:
netsh advfirewall firewall add rule name="Minecraft" dir=in action=allow protocol=TCP localport=25565
4. Configure Port Forwarding
If players outside your network cannot join, you must forward port 25565 to your server PC.
Follow the full guide: How to Port Forward a Minecraft Server
5. ISP or CGNAT Issues
If port forwarding is correct but it still fails:
- Check if your router shows a WAN IP that differs from your public IP
- Ask your ISP if they use CGNAT
- Consider a tunnel service or hosted server
Still Stuck?
See Common Server Errors for more fixes and a checklist.