Vintage Story Server Troubleshooting: Common Fixes

Vintage Story server problems usually come from a handful of repeatable causes: wrong port forwarding, a mismatched game version, corrupted world files, or a firewall silently blocking connections. This guide walks through the most common issues and gives step-by-step fixes you can apply in order, from quick checks to deeper file-level repairs.

First, Confirm the Basics

Before changing any settings, verify the three things that cause most connection failures. First, check that your game client and server are on the exact same version, including the same release channel (stable vs. release candidate). Second, confirm the server is actually running and listening on port 42420, the default Vintage Story port. Third, make sure you are trying to connect using the correct address: localhost for a server on the same machine, your LAN IP for a local network, and your public IP or a hostname for an internet server.

If the server console shows no errors but you still cannot connect, run a quick port check from another device on your network using an online port checker tool. If the port appears closed, the issue is almost always your router or firewall.

Port Forwarding and Firewall Fixes

For a server that friends outside your home network cannot reach, port forwarding is the usual culprit. The server needs TCP and UDP port 42420 forwarded to the computer running the server. Log into your router’s admin page (typically at 192.168.1.1 or 192.168.0.1), find the port forwarding section, and create a rule for both protocols pointing to the server’s local IP address. Give the server a static IP reservation in your router’s DHCP settings so the IP does not change on reboot.

On the server machine itself, Windows Firewall often blocks the game silently. Add an inbound rule for TCP and UDP port 42420, or allow the VintagestoryServer.exe executable through the firewall. If you are using a third-party firewall or antivirus with network protection, add an exception there as well.

If you are using a hosting provider or a VPS, check that the provider’s own firewall (sometimes called a security group or network firewall) also allows port 42420. Many providers block all inbound ports by default.

Version Mismatch and Mod Conflicts

A version mismatch is the most common reason a client connects, then disconnects with a “version mismatch” error. The server and client must match exactly, down to the patch number. If you updated the client but not the server, or vice versa, the connection will fail. The fix is to update both to the same version, or use the server’s version selector in the client to connect to an older server.

Mods add another layer. If the server uses mods, every client needs the same mods in the same versions. A missing or extra mod will cause a disconnect, often with a message listing the mismatched mods. The easiest fix is to copy the mods folder from the server to each client, or use a mod manager that syncs versions. If a mod causes a crash on startup, remove it from the server’s Mods folder and try again. Test with a vanilla server first to rule out mod issues.

World File Corruption and Backup Recovery

If the server crashes on startup or during play, the world file may be corrupted. Vintage Story saves worlds in the Saves folder inside the server directory. The game creates backups automatically, usually in a subfolder named Backups. To recover, stop the server, rename the current world folder (e.g., MyWorld to MyWorld_corrupt), then copy the most recent backup into the Saves folder with the original name. Restart the server and test.

If you do not have a backup, try running the server with the --repair command-line flag, which attempts to fix common world data issues. This is not guaranteed to work, but it is worth trying before starting a new world. Regular manual backups are the best prevention; copy the world folder to a separate drive or cloud storage after each play session.

Performance and Lag Issues

Server lag, where players experience rubber-banding or delayed block breaks, is often caused by insufficient RAM or CPU. Vintage Story servers are single-threaded for most world simulation, so a fast single-core CPU matters more than many cores. The recommended minimum is 4 GB of RAM for a small server, but 8 GB is safer for several players. Check the server’s memory usage in the console or task manager. If it is consistently near the limit, increase the maxMem setting in the server’s serverconfig.json file, or launch the server with a higher -Xmx Java parameter (e.g., -Xmx4G).

Another common lag source is a slow hard drive. Move the server to an SSD if possible. Also, reduce the server’s view distance and simulation distance in the config file if you have many players or a weak CPU. Lowering these values reduces the chunks the server has to process, improving responsiveness.

Connection Drops and Timeouts

If players connect but get disconnected after a few minutes, the issue is often a timeout caused by the server being overloaded or the network dropping packets. Check the server console for errors like “player timed out” or “connection reset.” Increase the timeout value in the server config (default is usually 30 seconds) to 60 or 90 seconds to give slow connections more time.

On the client side, a VPN or aggressive router settings can cause timeouts. Disable any VPN for the game, and in the router, disable SPI (Stateful Packet Inspection) or set the connection to “always on” if the option exists. Also, ensure the server’s system clock is accurate; a large time skew can cause auth failures.

Frequently Asked Questions

Why can I connect to my server locally but not from outside?

This is almost always port forwarding or firewall. Your router is not forwarding port 42420 to your server’s local IP, or your ISP is blocking inbound connections. Double-check the port forwarding rule, ensure the server has a static IP, and test the port from an external device. If it still fails, your ISP may be using CGNAT, which requires a VPN tunnel or a hosting service.

How do I change the server port from the default 42420?

Edit the serverconfig.json file in the server directory. Find the Port field and change it to your desired number. Restart the server. Remember to update the port forwarding rule and tell players to connect with the new port (e.g., your.ip:42421).

My server crashes on startup with a “OutOfMemory” error. What do I do?

This means the server does not have enough RAM allocated. Increase the maxMem setting in serverconfig.json or the -Xmx JVM argument. For example, set maxMem to 4096 for 4 GB. If the machine has little free RAM, close other programs or add more RAM to the system.

Can I run a Vintage Story server on a Raspberry Pi?

Technically yes, but it is not recommended. The server requires a 64-bit OS and at least 2 GB of RAM, which the Pi 4 or 5 can provide, but the CPU is weak for world simulation. Expect low tick rates and lag with more than one or two players. For a serious server, use a dedicated PC or a VPS with a fast single-core CPU.

How do I whitelist players on my server?

In the server console, type whitelist add [playername] to add a player, and whitelist remove [playername] to remove. You can also edit the whitelist.json file in the server directory. Enable whitelist mode by setting WhitelistMode to true in serverconfig.json.

Prevention and Maintenance

Most server problems are avoidable with a few habits. Always back up your world folder before updating the server or adding mods. Keep the server and clients on the same version, and read the changelog before updating to know if the world format changed. Monitor the server’s RAM usage and restart it periodically to clear memory leaks. If you are running many mods, test them on a separate world first.

For long-term stability, consider running the server on a dedicated machine or a VPS with a static IP. This avoids home network issues like dynamic IPs and power outages. If you use a dynamic DNS service, remember to update the address players use.

Finally, when you encounter a new error, copy the exact message from the server console and search the Vintage Story forums or Discord. The community has likely seen it before, and the fix is often a single config change.

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