diff --git a/.eslintrc.js b/.eslintrc.js
index 0764886b..3cf36d34 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -288,6 +288,7 @@ module.exports = {
 				":": "before",
 				"||": "before",
 				"&&": "before",
+				"??": "before",
 			},
 		}],
 		"padded-blocks": "off",
diff --git a/packages/host/src/Host.ts b/packages/host/src/Host.ts
index 436efe1b..a975fd09 100644
--- a/packages/host/src/Host.ts
+++ b/packages/host/src/Host.ts
@@ -599,7 +599,9 @@ export default class Host extends lib.Link {
 		let instanceConnection = this.instanceConnections.get(instanceId);
 		this.send(
 			new lib.InstanceStatusChangedEvent(
-				instanceId, instanceConnection ? instanceConnection.instance.status : "stopped", undefined
+				instanceId,
+				instanceConnection ? instanceConnection.instance.status : "stopped",
+				instanceConnection ? instanceConnection.instance.server.gamePort : this.gamePort(instanceId),
 			)
 		);
 
@@ -607,6 +609,10 @@ export default class Host extends lib.Link {
 		await this.sendSaveListUpdate(instanceId, path.join(instanceInfo.path, "saves"));
 
 		// save a copy of the instance config
+		await this.saveInstanceConfig(instanceInfo);
+	}
+
+	async saveInstanceConfig(instanceInfo: { path: string, config: lib.InstanceConfig }) {
 		let warnedOutput = {
 			_warning: "Changes to this file will be overwritten by the controller's copy.",
 			...instanceInfo.config.toJSON(),
@@ -647,6 +653,50 @@ export default class Host extends lib.Link {
 		return instanceInfo;
 	}
 
+	/**
+	 * Retrieved assigned port of the given instance
+	 * @param instanceId - ID of the instance to get the assigned game port of:
+	 * @returns Assigned game port or undefined if it does not exist.
+	 */
+	gamePort(instanceId: number) {
+		const instance = this.discoveredInstanceInfos.get(instanceId);
+		if (!instance) {
+			return undefined;
+		}
+		return (
+			instance.config.get("factorio.game_port")
+			?? instance.config.get("factorio.host_assigned_game_port")
+			?? undefined
+		);
+	}
+
+	assignGamePort(instanceId: number) {
+		const availablePorts = lib.parseRanges(this.config.get("host.factorio_port_range"), 1, 2**16 - 1);
+		for (const [id, instance] of this.instanceInfos) {
+			if (id === instanceId) {
+				continue;
+			}
+			const port = (
+				instance.config.get("factorio.game_port")
+				?? instance.config.get("factorio.host_assigned_game_port")
+			);
+			if (port !== null) {
+				availablePorts.delete(port);
+			}
+		}
+		const instanceToAssign = this.instanceInfos.get(instanceId)!;
+		const assignedPort = instanceToAssign.config.get("factorio.host_assigned_game_port");
+		if (assignedPort !== null && availablePorts.has(assignedPort)) {
+			return assignedPort;
+		}
+		if (!availablePorts.size) {
+			throw new lib.RequestError("No available port left to assign from host.factorio_port_range");
+		}
+		const [newPort] = availablePorts;
+		instanceToAssign.config.set("factorio.host_assigned_game_port", newPort);
+		return newPort;
+	}
+
 	/**
 	 * Initialize and connect an unloaded instance
 	 *
@@ -923,7 +973,7 @@ export default class Host extends lib.Link {
 			list.push(new lib.HostInstanceUpdate(
 				instanceInfo.config.toRemote("controller"),
 				instanceConnection ? instanceConnection.instance.status : "stopped",
-				instanceConnection ? instanceConnection.instance.server.gamePort : undefined,
+				instanceConnection ? instanceConnection.instance.server.gamePort : this.gamePort(instanceId),
 			));
 		}
 		await this.send(new lib.InstancesUpdateRequest(list));
@@ -986,6 +1036,10 @@ export default class Host extends lib.Link {
 
 		logger.info("Saving config");
 		await lib.safeOutputFile(this.configPath, JSON.stringify(this.config, null, "\t"));
+		for (const instanceInfo of this.instanceInfos.values()) {
+			// Save in case host_assigned_game_port changed in the config.
+			await this.saveInstanceConfig(instanceInfo);
+		}
 
 		try {
 			// Clear silly interval in pidfile library.
diff --git a/packages/host/src/Instance.ts b/packages/host/src/Instance.ts
index 09acb34c..3fda98ec 100644
--- a/packages/host/src/Instance.ts
+++ b/packages/host/src/Instance.ts
@@ -169,7 +169,7 @@ export default class Instance extends lib.Link {
 		let serverOptions = {
 			logger: this.logger,
 			version: this.config.get("factorio.version"),
-			gamePort: this.config.get("factorio.game_port") ?? undefined,
+			gamePort: this.config.get("factorio.game_port") ?? host.assignGamePort(this.id),
 			rconPort: this.config.get("factorio.rcon_port") ?? undefined,
 			rconPassword: this.config.get("factorio.rcon_password") ?? undefined,
 			enableWhitelist: this.config.get("factorio.enable_whitelist"),
@@ -449,7 +449,7 @@ rcon.print(game.table_to_json(players))`.replace(/\r?\n/g, " ");
 			new lib.InstanceStatusChangedEvent(
 				this.id,
 				status,
-				status !== "stopped" ? this.server.gamePort : undefined,
+				this.server.gamePort,
 			),
 		);
 	}
diff --git a/packages/lib/src/config/definitions.ts b/packages/lib/src/config/definitions.ts
index eb5dbb51..fd691557 100644
--- a/packages/lib/src/config/definitions.ts
+++ b/packages/lib/src/config/definitions.ts
@@ -158,6 +158,7 @@ export interface HostConfigFields {
 	"host.controller_token": string;
 	"host.tls_ca": string | null;
 	"host.public_address": string;
+	"host.factorio_port_range": string;
 	"host.max_reconnect_delay": number;
 }
 
@@ -220,6 +221,14 @@ export class HostConfig extends classes.Config<HostConfigFields> {
 			type: "string",
 			initialValue: "localhost",
 		},
+		"host.factorio_port_range": {
+			title: "Factorio port range",
+			description:
+				"Range of UDP ports to use for game connections. Supports both comma separated values and " +
+				"ranges separated with a dash.",
+			type: "string",
+			initialValue: "34100-34199",
+		},
 		"host.max_reconnect_delay": {
 			title: "Max Reconnect Delay",
 			description: "Maximum delay to wait before attempting to reconnect WebSocket",
@@ -237,6 +246,7 @@ export interface InstanceConfigFields {
 
 	"factorio.version": string;
 	"factorio.game_port": number | null;
+	"factorio.host_assigned_game_port": number | null;
 	"factorio.rcon_port": number | null;
 	"factorio.rcon_password": string | null;
 	"factorio.player_online_autosave_slots": number;
@@ -286,11 +296,16 @@ export class InstanceConfig extends classes.Config<InstanceConfigFields> {
 			initialValue: "latest",
 		},
 		"factorio.game_port": {
-			description: "UDP port to run game on, uses a random port if null",
+			description: "UDP port to run game on, uses a port in host.factorio_port_range if null",
 			restartRequired: true,
 			type: "number",
 			optional: true,
 		},
+		"factorio.host_assigned_game_port": {
+			access: ["host"],
+			type: "number",
+			optional: true,
+		},
 		"factorio.rcon_port": {
 			description: "TCP port to run RCON on, uses a random port if null",
 			restartRequired: true,
diff --git a/test/host/Instance.js b/test/host/Instance.js
index 9af3921d..723bd776 100644
--- a/test/host/Instance.js
+++ b/test/host/Instance.js
@@ -20,7 +20,7 @@ describe("class Instance", function() {
 		instanceConfig.set("instance.name", "foo");
 		src = addr({ instanceId: instanceConfig.get("instance.id") });
 		connector = new MockConnector(src, dst);
-		instance = new Instance({}, connector, "dir", "factorioDir", instanceConfig);
+		instance = new Instance({ assignGamePort: () => 1 }, connector, "dir", "factorioDir", instanceConfig);
 		instance.server = new MockServer();
 	});