Project Zomboid connection trouble is almost always ports, the public setting, or a mod mismatch. Here's how to make the server reachable and keep mods in sync.
Quick answer
A Project Zomboid server that does not show is usually a closed port, the public setting or a mod mismatch. Open UDP 16261 and 16262, set Public=true in servertest.ini to list it, and make sure every player has the server's mods. For a private server, skip the browser and join directly by IP and port.
Open the ports
PZ uses a UDP range. Open/forward these to the server:
16261/udp default port
16262-16272/udp extra ports (one per player on some setups)Set it public (or just join by IP)
To list in the public browser, set Public=true in the server config. For a private/friends server, skip the browser and connect directly — more reliable anyway:
# servertest.ini
Public=true
PublicName=My PZ Server
DefaultPort=16261To join directly: Project Zomboid → Join → Favorites/Add → enter server-ip and port 16261.
Mods must match — in the same order
A mod mismatch stops players joining. The server's WorkshopItems and Mods lists must match what clients subscribe to, in the same order:
WorkshopItems=2392709985;2200148440
Mods=tsarslib;ModManagerWhen a mod updates, restart the server so it pulls the new version — otherwise players on the new version can't join the old server.
Open 16261/udp, set Public or join by IP, and keep WorkshopItems + Mods matching the clients in the same order.
The WorkshopItems vs Mods gotcha
These two lines do different jobs and both must be right. WorkshopItems lists the Steam Workshop IDs to download; Mods lists the internal mod names to actually load. A mod can download (WorkshopItems correct) yet never activate because its name is missing or misspelled in Mods — and some Workshop items contain multiple mods with several names. Check the mod's Workshop page for the exact Mod ID string to put in the Mods line.
Why a PZ server isn't showing even with Public=true
- The server needs a few minutes after boot to register with the public browser.
- A firewall on the server OS blocking the UDP range even though the router forwards it.
- Behind CGNAT there is no way to accept inbound connections — see our port forwarding guide.
- A crashed mod on startup can stop the server finishing its boot and ever listing.
How to prevent Project Zomboid connection and mod problems
Change one mod at a time and test joining after each, so a mismatch is easy to trace. Keep a backup of servertest.ini before editing the mod lists, and always restart the server after any mod update rather than leaving it running on the old version.
Related Project Zomboid guides
For a full setup walkthrough, see how to make a Project Zomboid server, then tune zombies, loot and XP with our best Project Zomboid server settings. For mod recommendations, see best Project Zomboid mods. If ports look correct but players still time out, revisit how to port forward a game server and "Connection timed out" joining a game server. Our Project Zomboid hosting opens these ports for you.
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