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; the app's Network page shows your profile's ports).

  1. In the app, open Network and copy this PC's local IP (something like 192.168.1.20).
  2. Still on Network, 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 (on 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. On Network, copy the modpack code and send it to your friends. They paste it into Check my game (in their app) and see what is missing.
  4. Password and whitelist. By default the server only lets in people who know the password. The invite can include it (with a warning).
  5. Windows Firewall. Does Network show "Done" for the firewall step? If not, press "Create rule…".
  6. Router. Follow the guide above. Friends in the same home use the local IP; from outside, the public IP.
  7. Look at Logs. In the app, Logs › Errors 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 Workshop › Import collection.
  2. The app finds each item's Mod IDs and adds the dependencies already downloaded, in the right order. If an item has several mods, you choose which.
  3. Missing mods download with More actions › Download missing, or subscribe in the game's Workshop.
  4. Press Check everything: it points out wrong IDs, missing dependencies and mods for another Build.
  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. When the notice "The profile has changes that are not in the server .ini yet" appears, press Write to .ini… and restart the server.

Something broke? Mod history restores the last list that worked.