Insurgency Sandstorm / UPDATED April 26, 2026

How to Troubleshoot Players Unable to Connect to Your Insurgency Sandstorm Server

Work through connection problems step by step — from firewall ports to version mismatches and mod conflicts, most issues have a quick fix.

Insurgency Sandstormconnection issuestroubleshootingportsfirewall

Required Ports

IS requires these ports to be open and accessible:

Port	Protocol	Purpose
`27102`	UDP	Game traffic (default; configurable in Engine.ini)
`27131`	UDP	Steam query port (server browser listing)
`27015`	TCP	RCON (only needed if using RCON)

Check your control panel's firewall or port settings and confirm UDP 27102 and 27131 are open. A closed query port means the server won't appear in the community browser, but players can still direct connect. A closed game port means no one can connect at all.

Step-by-Step Diagnosis

1. Check the Server Logs for Startup Errors

Before anything else, open the latest log file in Insurgency/Saved/Logs/. Look for lines with Error or Warning near the top. Common fatal errors:

Map not found — a map name in MapCycle.txt is misspelled or the map wasn't installed.
Mod download failure — mod.io is unreachable, or a mod ID in Mods.txt no longer exists.
Port already in use — another process is bound to your game port.

Fix any errors shown here before proceeding.

2. Verify Ports Are Open

Use an external port checker (search "UDP port checker" — several free web tools exist) to test UDP 27102 from outside your network. If it comes back as closed or filtered, the issue is at the firewall level in your control panel.

3. Check the Server Browser

Search for your server in IS's community browser (in-game under Play > Community Server Browser). It can take 2–5 minutes after a server start for the listing to appear. If your server doesn't show up after 10 minutes:

Confirm bEnabled=True is set under [OnlineSubsystemSteam] in Engine.ini.
Confirm the query port (27131) is open.

4. Try Direct Connect

Even if the browser listing is missing, players can try direct connect:

In IS, go to Play > Find Server > Direct IP.
Enter yourserverip:27102.

If direct connect works but browser listing doesn't, the problem is with the query port or Steam's server list propagation time.

5. Check for a Version Mismatch

If players see a version mismatch error, your server is running a different IS version than their client. This is the most common reason players can't connect after a game update.

Update your server immediately. See How to Update Your Insurgency Sandstorm Server.
After updating, confirm the version in your logs matches what players see in their IS main menu.

6. Check for a Mod Mismatch

If your server has mods enabled in Game.ini via ActiveMods, clients without those mods will be rejected on join. Players need to subscribe to the same mods on mod.io before connecting.

Temporarily remove all ActiveMods= entries from Game.ini and restart to test if the issue is mod-related.
If removing mods fixes connectivity, add them back one at a time to find the problem mod.

7. Confirm the Server Is Actually Running

It sounds obvious, but check your control panel to confirm the server process is online and hasn't crashed silently. Some crashes produce no visible error in the panel but the process is no longer running.

Still Stuck?

If you've worked through all the steps above and players still can't connect, contact our support team with:

Your server's IP and port
The relevant portion of your startup logs
The exact error message players are seeing