Knox Safehouse
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Guides

The most common problems, solved step by step.

Opening ports on the router (port forwarding)

For friends to join over the Internet, your home router must let the server's traffic through to your PC. Project Zomboid uses UDP 16261 and 16262 (the defaults; in the app, Friends › Network shows your server's ports).

  1. In the app, open Friends › Network and copy this PC's local IP (something like 192.168.1.20).
  2. Still there, press Create rule…. Windows asks once: it is the firewall rule, only for these ports and only on private networks.
  3. Open your router's page in the browser (usually 192.168.1.1 or 192.168.0.1; it is on a label on the router) and sign in with the router's password.
  4. Look for Port forwarding, NAT or Virtual servers.
  5. Create a rule for UDP 16261 and another for UDP 16262, both pointing to the local IP from step 1.
  6. Save. Friends join with your public IP (in Friends › Network, "Show my public IP") and port 16261.

Can't open ports?

Some providers use CGNAT (your router's public IP is shared) and port forwarding cannot work. Alternative: a virtual network VPN (for example Radmin VPN or Hamachi). You and your friends join the same virtual network and connect to the VPN IP. The app does not install any of this for you.

Never open the RCON port on the router. The app keeps RCON off and writes UPnP=false, so the server never opens ports by itself.

Friends can't get in

Check in this order; most problems are solved in the first three.

  1. Is the server really on the air? In the app the state must be "On the air" (green), not "Starting". The first start can take a few minutes.
  2. Same game version. If the server is on Build 42 (public branch), your friends must be too; the branch is shown on the app's Home.
  3. Same mods. Usually the game downloads the server's mods when they join. If one is missing, copy the modpack code (Friends › Network) and send it; anyone with the app pastes it into Settings › Help › Check my game and sees what is missing.
  4. The password. Anyone who knows the server password gets in (the invite can include it, with a warning). If you turned on the whitelist, only the players you added in Server › Add player… get in.
  5. Windows Firewall. In Friends › Network, does the firewall step say "Created"? If not, press "Create rule…". If Windows marked your network as Public, choose "Change networks…".
  6. Router. Follow the guide above. Friends in the same home use the local IP; from outside, the public IP.
  7. Look at the log file. Server › Log file shows what the server said when your friend tried to join.

Adding Workshop mods

  1. In Mods, paste a Workshop mod link (or just its number) and press Add. A whole collection goes in through the Workshop tab, with Import collection.
  2. The app finds each item's Mod IDs and also adds the mods it needs, in the right order (the ones not on the PC yet are downloaded). If an item has several mods, you choose which.
  3. If one is still missing, press More actions › Download missing.
  4. Press Check everything: it points out wrong IDs, missing mods and mods made for another Build. Checking changes nothing.
  5. Drag to change the order (or Alt+↑/↓). If something loads before a dependency, the row gets a warning; Sort by dependencies shows the "before → after".
  6. The list reaches the server by itself on the next start. To send it now, press Apply to the server and restart the server.

Something broke? The History tab (in Mods) puts back the last list that worked.