Verified practical guide

How to Run Multiple Arma 3 Servers on One Host Without Port Conflicts

Multiple Arma 3 dedicated-server processes can run from one installation. Each instance should use a unique port range and separate configuration.

Multiple Arma 3 dedicated-server processes can run from one installation. Each instance should use a unique port range and separate configuration, profile, mission, and key directories.

Allocate complete port blocks

For the default base port of 2302, Arma 3 documents this UDP allocation:

| Port | Purpose | |---:|---| | 2302 | Game traffic and VON | | 2303 | Steam query traffic | | 2304 | Steam master traffic | | 2305 | Allocated VON port, currently documented as unused | | 2306 | BattlEye traffic |

Open the complete 2302–2306/UDP block in the host firewall and forward it when required by the host's NAT configuration.

Bohemia recommends leaving at least 100 ports between the base ports of successive instances. Its documented two-instance layout is:

| Instance | Base port | UDP block | |---|---:|---:| | Alpha | 2302 | 2302–2306 | | Bravo | 2402 | 2402–2406 |

The documentation warns that narrowly spaced base ports, such as 2302 and 2314, can cause the second server to report through the first server's query range.

Isolate each instance

Arma 3 supports running multiple instances from a shared installation by assigning separate values for -port, -profiles, -mpmissions, and -keysFolder. Each process can also select its own server configuration with -config.

A Windows launch script following that arrangement can look like this:

@echo off
start "Arma 3 Alpha" arma3server_x64.exe ^
  -port=2302 ^
  -name=Alpha ^
  -profiles="Instances\Alpha\Profiles" ^
  -config="Instances\Alpha\server.cfg" ^
  -mpmissions="Instances\Alpha\MPMissions" ^
  -keysFolder="Instances\Alpha\Keys"

start "Arma 3 Bravo" arma3server_x64.exe ^
  -port=2402 ^
  -name=Bravo ^
  -profiles="Instances\Bravo\Profiles" ^
  -config="Instances\Bravo\server.cfg" ^
  -mpmissions="Instances\Bravo\MPMissions" ^
  -keysFolder="Instances\Bravo\Keys"

Set a distinct hostname in each configuration because this setting supplies the name displayed in the public server list.

Verify Steam discovery

Arma 3 registers game servers with Steam for discovery. Its Steam query integration reports information including the server name, maximum player count, map, password-protection state, and filtering tags.

Check the Arma 3 or Steam server browser to confirm that each hostname appears independently and corresponds to the intended instance.

The dedicated-server package is Steam application 233780. Bohemia's installation instructions use app_update 233780 validate to install or update it.

Sources and verification

Dedicated Server – Arma 3Documents the UDP port allocation, firewall and forwarding requirements, 100-port spacing recommendation, query-range conflict example, shared-installation parameters, per-instance isolation, hostname behavior, and SteamCMD installation command.
Server Config File – Arma 3Documents server configuration selection and the hostname displayed in the public server list.
STEAMWORKSquery – Arma 3Documents Steam server registration and the server name, player capacity, map, password state, and filtering information reported to Steam.
Arma 3 Server on SteamIdentifies Arma 3 Server as Steam application 233780.