fire alarms will now attempt to register and sync against all connected devices whenever a device list is updated

Content.Server/Atmos/Monitor/Systems/FireAlarmSystem.cs

@@ -1,5 +1,6 @@
 using Content.Server.AlertLevel;
 using Content.Server.Atmos.Monitor.Components;
+using Content.Server.DeviceNetwork.Systems;
 using Content.Server.Power.Components;
 using Content.Server.Power.EntitySystems;
 using Content.Shared.AlertLevel;
@@ -12,15 +13,23 @@ namespace Content.Server.Atmos.Monitor.Systems
 {
     public sealed class FireAlarmSystem : EntitySystem
     {
+        [Dependency] private readonly AtmosDeviceNetworkSystem _atmosDevNet = default!;
         [Dependency] private readonly AtmosAlarmableSystem _atmosAlarmable = default!;
         [Dependency] private readonly SharedInteractionSystem _interactionSystem = default!;
 
         public override void Initialize()
         {
             SubscribeLocalEvent<FireAlarmComponent, InteractHandEvent>(OnInteractHand);
+            SubscribeLocalEvent<FireAlarmComponent, DeviceListUpdateEvent>(OnDeviceListSync);
             SubscribeLocalEvent<FireAlarmComponent, GotEmaggedEvent>(OnEmagged);
         }
 
+        private void OnDeviceListSync(EntityUid uid, FireAlarmComponent component, DeviceListUpdateEvent args)
+        {
+            _atmosDevNet.Register(uid, null);
+            _atmosDevNet.Sync(uid, null);
+        }
+
         private void OnInteractHand(EntityUid uid, FireAlarmComponent component, InteractHandEvent args)
         {
             if (!_interactionSystem.InRangeUnobstructed(args.User, args.Target))

Resources/Prototypes/Entities/Structures/Wallmounts/fire_alarm.yml

@@ -13,6 +13,8 @@
     deviceNetId: AtmosDevices
     receiveFrequencyId: AtmosMonitor
     transmitFrequencyId: AtmosMonitor
+    sendBroadcastAttemptEvent: true
+  - type: DeviceList
   - type: ApcNetworkConnection
   - type: AtmosMonitor
     monitorFire: true