Contents
TROUBLESHOOTING
When joining Project Zomboid, you may see "WARNING: SERVER HAS PORT … CLOSED. PERFORMANCE MAY BE SEVERELY AFFECTED" on the loading screen. This message appears when the second port is not reachable. You can fix this in the game panel.
Revision History
- v1.0
- October 2026 — Initial version created
About This Warning
Project Zomboid servers use 2 ports. If the second port is not reachable, the following warning will appear on the loading screen when joining:WARNING: SERVER HAS PORT … CLOSED. PERFORMANCE MAY BE SEVERELY AFFECTED
When this occurs, communication switches to a method that routes through Steam, which may cause latency.Normally, both ports are automatically assigned, so this procedure is not necessary. Only perform the following steps in rare cases when the second port is not assigned.
First, Check
Console Display
In the Console tab, check the2 本目のポート (Second port) field displayed at startup. If it shows ★Not found, a second port has not been assigned.Number of Ports in Network Tab
Open the Network tab to see the assigned ports listed.- If there is only 1 line … Follow the steps starting from step 1 in "How to Fix" below
- If there are 2 lines but a warning appears … Follow the steps starting from step 3 in "How to Fix" below
The line marked Primary is the CONNECT destination port (the number to share with your friends).
How to Fix
- Open the Network tab and check if there are 2 port rows.
- If there is only 1 row, click "Create Allocation" (
Create Allocationin English panel) once.
If there are already 2 rows, this button will not be displayed. In that case, proceed to step 3. - Note the port number of the row that is not primary (only the port number, not the IP address).
- Enter the noted number in
[NETWORK] Second Port (UDP)on the Startup tab. - Restart the server from the Console tab and verify that the number from step 3 is displayed in the
2 本目のポート(Second port) field.
If ★Not found appears in the console, add one port and restart; it will be used automatically (steps 1, 2, and 5 alone may resolve the issue).
This will enable the second port to receive traffic.Notes
You can add up to 2 ports
Up to 2 ports including the primary port. If you see a warning even though both ports exist, follow steps 3-5.Do not delete ports
- Deleting the primary (main port) will change your CONNECT. The number you shared with your friends will no longer work
- Deleting the second port will cause the warning to appear again
[NETWORK] Second Port (UDP) to the current number or clear it before restarting.
