How to Fix Can't Connect to Game Server Errors (Checklist)

Start with the symptom

Step 1: Is the server actually up?

Open your server in the control panel and check that it's running, not stopped or still starting. Large worlds and modded servers can take minutes to finish loading, and a server that's still booting will refuse or time out connections.

• Watch the console until you see the game's "ready" or "done" message.
• Check the server's player count and resource usage. A flat line at maximum CPU or a crash-restart loop explains many join failures.
• Confirm the server isn't full. Minecraft's max-players defaults to 20, and a full server turns players away.
• Look at the last lines of the log for errors such as a missing file, bad config value or a mod that failed to load.

If the server crashed on startup, nothing in the rest of this guide matters yet. Fix the crash first, usually by reverting your last config or mod change.

Step 2: Check the IP address, game port and query port

Use the exact IP and port shown in your control panel. Hosted servers often have a port other than the game's default, and typing only the IP uses the default port, which may be the wrong one. Common causes at this step: a typo, a copied address with a trailing space, an old IP after a migration, or a custom domain whose DNS record hasn't updated.

Game port vs Steam query port. Many Steam games use two different kinds of traffic. Players join on the game port. The server list, Steam's favourites and server-browser tools ask for the server's details with a separate query (A2S) request, often on a different port. Valve's documentation describes it as a UDP query that returns the server's name, map and player count.

• If direct connect works but the server isn't in the list, the server is fine. Suspect the query port, list delay or filters (map, password and session filters hide servers more often than you'd expect). Search for a distinctive word in the name, or add the server to your favourites using the IP and query port.
• If neither works, go back to step 1 and the address checks above.
• A server that is listed but won't accept joins usually means the query port is reachable but the game port isn't, or there is a version or password problem (steps 3 and 4).

Step 3: Version and mod mismatches

Most games refuse to connect when client and server versions differ. Messages vary by game and version ("Outdated client", "Incompatible client", "Outdated server"), but the fix is the same: make both sides run the same version.

• Minecraft Java has no built-in cross-version support. Change the launcher profile to match the server, or update the server. If your server uses a proxy, the proxy decides which versions are accepted. Minecraft versions now follow the year-based style (26.1 and later), so "1.21" and "26.x" don't match.
• Valheim servers and clients need to be on the same version, so after an update players on an old client can't connect until they update too.
• Modded servers usually need matching mods: Forge, Fabric and NeoForge servers show messages listing the missing or mismatched mods. 7 Days to Die's wiki says the server and every client must run matching mod and game versions. Server-side plugins (Paper, Oxide, Carbon) need nothing on the client.
• A game update came out overnight? Steam clients auto-update, but the server may not, or the reverse. Check both.

Step 4: Passwords, whitelists and authentication

• Wrong password: retype it; check for caps lock and trailing spaces. In Valheim, passwords must be at least five characters and can't appear in the server name.
• Whitelist: in Minecraft, "You are not white-listed on this server" means the player isn't on whitelist.json. Add them with whitelist add <name>, then whitelist reload if you edited the file by hand. In Valheim, a non-empty permittedlist.txt shuts out everyone who isn't on it.
• Authentication: with online-mode on (the default), Minecraft checks each player against Mojang's account service. "Failed to verify username" or an invalid session message means the account or launcher session is the problem: restart the game and launcher and sign in again. Don't turn online-mode off to "fix" it; that lets anyone join under any name.
• Bans: check the ban list. A player on a shared network can be caught by an IP ban.

Step 5: Problems on the player's side

If the server shows as running, other players can join and only one person can't, the cause is on their end.

• Try another network. A phone hotspot is the quickest test. If it works there, your home network, ISP or a VPN is the cause.
• Turn off the VPN and any security software that filters traffic, then retry. Some VPNs block game ports or use routes that don't reach the server.
• Windows Firewall or antivirus may be blocking the game itself. Allow the game through for private and public networks.
• IPv6: if a hostname resolves to an IPv6 address on the player's network and the game struggles with it, connect with the numeric IPv4 address instead.
• Wi-Fi and routers: restart the router, and test on a cable if you can.
• Check the route. Run ping and tracert (Windows) or traceroute to the server's IP. If traffic dies partway, the break is on the path, and your ISP should hear about it. Our guide to ping, latency and server location explains how to read the output.

A ping that gets no reply isn't conclusive, because some servers and networks ignore ping. A game-specific connection attempt is the real test.

Step 6: Read the logs

The log tells you whether a connection attempt reached the server at all. Open the server's console or log file, ask the player to try joining, and watch.

• Nothing appears when the player tries: the traffic isn't reaching the server. Re-check the address, port, and the player's network and firewall.
• A connection or login line appears, followed by a rejection or error: the network is fine and the server turned them away. The reason is usually printed: version, whitelist, password, mods or ban.
• Errors on startup: a config or mod problem is stopping the server from fully starting.

Some games let you set a log file location. Valheim's server has a -logFile launch option, for example. Whatever the game, copy the exact error text before you change anything.

When to contact support

If the server is running, the address is right, versions match and the log shows nothing helpful, ask your host. You'll get a faster answer if you include:

• The game, the server address (IP and port), and the exact error message.
• What you changed last (mod, config, update, migration) and when it last worked.
• Whether other players can connect, and whether the affected player has tried another network.
• A traceroute or pathping result from the affected player, and the relevant log lines.

Frequently asked questions