add instructions to fix linked devices

doc/TROUBLESHOOTING.md

@@ -1,21 +1,59 @@
 ## Troubleshooting
 
-_Work in progress._
-
 If the following doesn't help you, do feel free to
 [file an issue](https://github.com/pcrockett/mollysocket-fly/issues). If you include the output of
 `make logs` in your issue description, that would be very helpful.
 
-**The Molly app stops receiving notifications after a while.**
+If the Molly app stops receiving push notifications, there could be a number of reasons:
+
+### You forgot to restart / redeploy the MollySocket server after adding your device
+
+Try restarting the server with `flyctl deploy`.
+
+### You have too many linked devices:
+
+Signal only allows 3 linked devices per account. MollySocket counts as 1 linked device, so if you've
+linked more than 2 other devices, you risk MollySocket being bumped off and it will never reconnect
+again.
 
-If you recently added a new connection to your MollySocket server, restart the server with
-`flyctl deploy` if you haven't already.
+To see if this is the case, go into the Molly Android app settings and select _Linked devices_. You
+should see your current Android device in the list, _MollySocket_, and up to 2 other devices.
+
+If you don't see _MollySocket_ in the list, you know MollySocket has been disconnected. Try these
+steps:
+
+1. If you see 3 or more linked devices in your list, remove one of them by tapping on it.
+2. Login to your server with `flyctl ssh console`
+3. Run `mollysocket connection list`. It should output something like this:
+   ```plaintext
+   [src/cli/connection.rs:109:13] &connection = Connection {
+       uuid: "....",
+       device_id: ...,
+       password: "...",
+       endpoint: "...",
+       forbidden: true,
+       last_registration: OptTime(
+           None,
+       ),
+   }
+   ```
+4. Run `mollysocket connection remove <the uuid displayed above>`
+5. Type `exit` and then `flyctl deploy` to restart the server.
+6. Re-add the connection as described in the [setup instructions](./HOWTO.md#setup-the-molly-app-for-push-notifications).
+7. Restart the server again
+
+After your server is up and running again, you should see MollySocket in your list of linked
+devices.
+
+### Your Android device is still doing battery optimization
 
 Double-check that battery optimization for both the UnifiedPush distributor AND Molly is disabled.
 If you have already disabled battery optimization, and you're not running some custom Android ROM
 on your phone, check out [dontkillmyapp.com](https://dontkillmyapp.com/) to see if there are
 additional hoops you need to jump through to prevent your phone from killing apps.
 
+### You are using a wonky UnifiedPush distributor app
+
 If you chose to use a UnifiedPush distributor other than `ntfy`, it very well
 [may stop working](https://github.com/mollyim/mollysocket/issues/35#issuecomment-2105094828). Try
 switching to `ntfy` (at least temporarily) to see if it resolves the problem.