[Minecraft] Causes and complete solution guide for not being able to access or connect to the server – ゲーム攻略まとめ

When trying to enjoy multiplayer in Minecraft, have you ever experienced problems such as “unable to connect to the server”, “connection times out”, or “unable to play with friends”? These connection errors can be caused by multiple factors, including misconfigurations, network issues, and server-side configuration. In this article, we will carefully explain countermeasures for each cause, with reference to actual trouble cases.

Types of error messages that cannot be connected

There are several common messages associated with Minecraft connection errors, each of which can give you a hint as to the cause. For example:

“Connection timed out” → Communication may have been interrupted midway.
“Connection refused” → Server not responding or port configuration problem.
“Unknown host” → IP address/domain name typo or DNS problem.
It is important to narrow down the cause based on these tips.

1. Basic check: Start here

Check server status

The basic problem with connection is whether the server is running in the first place. You cannot connect if the server is down, crashed, or unresponsive due to high load. Be sure to check the admin panel and logs to see if the server is running.

Server address and port number

If the server address or port number when connecting is incorrect, the connection will always fail. Be especially careful about misspelling periods and numbers. Make sure to enter the port number (usually 25565) exactly, for example 123.123.123.123:25565.

2. Network-related issues and solutions

Line or Wi-Fi instability

If communication is unstable, it may time out before connecting. When using Wi-Fi, radio wave interference and router performance may be affected, so if possible, switching to a wired (Ethernet) connection will often improve the situation. Refreshing the line by restarting your router or modem may also help.

Port forwarding (router settings)

If you are hosting the server on your own machine, you will need port forwarding settings on your router. Minecraft uses TCP port 25565 by default. If communication to the server on this port is blocked on the router side, external connections will not be possible. From the router’s management screen, let’s add a setting to forward port 25565 to the server’s IP address.

As a side note, setting a static IP address inside your router will prevent the internal IP from changing every time and invalidating your forwarding settings.

3. Firewall and security software

The standard Windows Firewall or third-party security software such as Norton or McAfee often block Minecraft connections. To avoid this, add Minecraft and Java executables (such as javaw.exe for the Java version) to your Firewall exceptions to allow communication on both private and public networks.

It may be helpful to temporarily turn off your antivirus and test the connection, but be sure to turn it back on after you finish.

4. Version differences and editions

Minecraft has a Java version and an integrated version (Bedrock), but they are not compatible. You can’t connect to a Java server with the integrated client, so be sure to make sure your Minecraft edition and server version are the same.

Also, connection errors can occur even if the versions of the server and client are slightly different. If you have installed mods or plugins, it is important to match the mod versions as well.

5. ISP (Internet Service Provider) Restrictions

In rare cases, the Internet service provider may restrict port forwarding or certain communications. Also, if a public IP is shared by CGNAT (Carrier-Grade NAT), port forwarding may not work and you may not be able to connect. In this case, you should contact your provider or try a different network environment.

6. Common trouble examples

Many cases have been reported from actual users, such as “Even though the server is running, I can’t connect from outside” and “I’ve set up port forwarding, but the port won’t open.” In some cases, the solution has been to check the port openings online and review the internal IP settings and detailed firewall rules.

Final checklist

This is a checklist that allows you to check the contents explained so far at once.

Check the log to see if the server is starting
Is the server IP/port accurate?
Is the network connection stable?
Have you configured port forwarding on your router?
Is there an exception setting for firewall/security software
Does the edition and version match?
Are there any restrictions on the ISP side?

Summary

Minecraft server connection problems can have a wide variety of causes, but most can be resolved by carefully checking each one. Make sure to carefully review your network, port settings, firewall, and version control to create a comfortable multiplayer environment. If the problem persists, consider contacting your server provider or network specialist.