Networking

Your server’s network configuration determines who can connect, and how. Players on the same network can use the server’s LAN address, but players over the internet need a way to reach the local server port.

You can configure port forwarding on your router, or use playit.gg for tunneling without changing your router settings. Both methods allow players outside of your local network to join the server.

Note

If you’ve already configured the host/network and are having connection issues, follow Troubleshooting

LAN configuration

Inside of auto-mcs, the IP/port combo box can be configured with an IP, a port, or both. Generally, you’d want to modify the port if you are planning on having multiple servers running on the same network interface at the same time.

Tip

You only need to change the IP address portion if you have multiple network interfaces on the host; e.g. Wi-Fi & Ethernet on two separate networks. By default, when the IP portion is blank, the server listens on all network interfaces: *:25565

If you’re playing Minecraft on the same computer that’s running auto-mcs, you can connect to the server using the localhost address. Otherwise, a running server’s LAN address is displayed in the Server Manager. This can be copied & pasted in-game to join, for instance, in Direct Connection:

Static addressing

Although optional, it’s recommended to configure static IPv4 addressing instead of using DHCP on the computer running auto-mcs. Static addressing for a computer running a networked service provides a consistent IP address to reference on your local network.

DHCP addressing is both temporary, and usually configured by default; for instance, if you have a saved Minecraft server or routing rules pointing to a leased DHCP address, your computer’s IP address can change when the lease expires. These references may no longer point to the right place, and if it does change, each reference will need to be updated with the new address.

Note

You can statically configure IP addresses on specific computers even with DHCP enabled on your router. Even though DHCP conflict detection can usually prevent assigning your static address to another device, it’s recommended to add the static assignment as an address reservation in the DHCP server (usually your router)

WAN/internet configuration

Due to most consumer routers utilizing Network Address Translation (NAT), a feature to map multiple LAN devices to a single public IP, port forwarding/triggering or the use of a proxy is required to forward traffic on a server between the internet and a LAN device.

Note

If you see an address beginning with 192.168.x.x, 10.x.x.x, or 172.16.x.x through 172.31.x.x, it’s a private LAN address. People outside your local network can’t use this to connect directly and you’ll need to configure WAN/internet access

Port forwarding

If you have administrative access to your router, apply a TCP rule with the LAN port that was configured during setup (default: 25565) to your router’s port forwarding configuration. If you’ve enabled Bedrock support (Geyser) in the additional settings, you’ll also need to apply a UDP rule on port 19132. If your router supports port triggering, you can enable that for the server’s LAN IP instead. Learn more about port forwarding here.

For a normal Java server on port 25565, the router rule forwards TCP 25565 to the computer’s LAN IP, also on port 25565. Additionally, auto-mcs can detect if your server is port forwarded correctly, and will display your public IP address in the Server Manager when possible.

For tunneling without router port forwarding, see playit.gg. For extra ports used by voice chat, Geyser, and other plugins, see Add-ons.

Caution

Port forwarding exposes your server’s port to incoming internet traffic while the forwarding rule is active. Keep your server updated and consider a whitelist for private servers. Using the built-in proxy avoids configuring a port-forwarding rule on your router.

Running multiple servers

auto-mcs can run as many servers as your hardware can support. Each running server needs a unique and available local port; if the server’s configured port is in use by another server or process, auto-mcs will check the nearby ports and temporarily assign an available one before launching the additional server.

For example, if one server is already using 25565, a second server configured with the same port may launch on 25566 instead. Check the Console for the warning:

The active port is used for that session, and auto-mcs will restore the configured port in server.properties when the server stops normally. If playit.gg is enabled, auto-mcs also looks for a tunnel using the new temporary port and will create a new tunnel if necessary. Either way, be sure to use the address displayed for that server rather than the first server’s address or port.

Note

If you’re using traditional port forwarding, the router rule must point to the port each server is actually using. For persistent setups, assign a different port to each server in Settings instead of relying on temporary conflict recovery