Project Zomboid asks for the address and the port in two separate boxes, and that detail causes more failed connections than everything else combined. Paste the whole IP:Port string into the IP box and the game answers "Unknown Host" and stops. Copy the two values separately and you are in inside a minute.
Copy the IP and the port
Open your server in the control panel and stay on the Overview tab. The connection card shows the IP and the port as two separate fields, each with its own copy button, because that is exactly how the game wants them.
Two things to know before switching to the game:
- Your port is almost certainly not 16261. That is the default for a server run at home, and it is the number nearly every guide online quotes. A rented server gets its own, so use what the panel shows.
- The IP field takes an IP and nothing else. No colon, no port, no
http://.
The Join button in the server header shows the same two values, so you can grab them without leaving whichever tab you are on.
Add the server
- Launch Project Zomboid and click Join on the main menu
- Open the Favorites tab
- Give the entry any name you like. It is only a label in your own list
- Paste the IP into IP, the IP alone
- Type the port into Port, replacing the 16261 already sitting there
- Leave Server Password empty unless the server has one
- Fill in Account Username and Account Password
That last step confuses people, so to be clear: you are choosing those, not entering something we issued. The pair becomes your character login on that server, and it is created the first time you join. Write it down.
- Click Add, select the server in the list, then Join Server
The first connection takes noticeably longer than later ones while the game pulls down map chunks and any mods.
Why you see "Unknown Host"
That message means the game could not make sense of what is in the IP box. In practice it is one of three things:
- The whole
IP:Portstring went into the IP box. Split it, everything after the colon belongs in Port - A space or a line break came along with the paste. Clear the box and paste again
- Something that is not a plain IPv4 address was typed. Use the value from the panel
If both fields are right and the game hangs or times out instead of erroring, the server is usually not ready. Check that the panel says it is running, and give it a minute after a start, because Project Zomboid loads the map before it accepts anyone.
Three different passwords
Project Zomboid has three, and mixing them up wastes a lot of time.
Server password. One shared value you set, and every player types it into Server Password on the join screen. It lives in the panel under Config, in the server browser section. A change to it applies after a restart, like the rest of the settings.
Account password. Chosen by each player on their first join and tied to that player's character. Nobody else needs to know it.
Admin password. A separate login that grants admin powers in game. It is not the same as either of the above.
Letting people search instead of typing an address
If you would rather players found the server by name, turn on the public browser listing in Config and set a server name. It then appears under the Internet tab in game.
Sharing the address is still faster, and it keeps working when the public list is slow to refresh, so treat the listing as a convenience rather than the main way in.
Joining a modded server
Mod lists have to match. A player who is missing a mod the server runs, or who has a different version of it, gets dropped during the handshake rather than at the address stage. That failure looks nothing like "Unknown Host", which is a useful signal in itself: an address problem fails before connecting, a mod problem fails after.
Subscribe to the same Steam Workshop items the server uses and the game loads them as you join.
Troubleshooting
Unknown Host. The IP box holds something that is not a bare IP. Nine times out of ten the port came along with it.
Times out with no error. The server is off, or still loading the map after a start.
You are not allowed to join this server. The whitelist is on and your account is not on it.
Kicked immediately on a modded server. Your mods do not match the server's.
Wrong username or password. Account Username and Account Password are per server. If you have forgotten them, an admin can remove the account so you can create it again on your next join.
Server is full. The slot cap is the max players value in Config.
Frequently asked questions
Do my friends need an account with you? No. They need the game, the IP and the port. The account they create on first join is stored on your server, not with us.
Can I use 16261? Only if that is genuinely what the panel shows. It is the standard default for home hosting, which is why so many guides mention it, but a rented server has its own port.
Why did my character disappear? Characters are tied to the account name you created on that server. Logging in with a different Account Username gives you a new character.
Does everyone need the same mods? Yes, and the same versions. That is the most common cause of being kicked seconds after connecting.
Still stuck on Unknown Host after splitting the address? Contact support with your server name and what you have in each of the two boxes, and we will check it from our side. No server yet? See our Project Zomboid server hosting plans.