Connecting multiple devices

One or two devices plug straight into the computer's ports and rarely cause trouble. A farm of dozens of phones is already an engineering task: power, cables, hubs and order on the desk. Below we cover how to assemble a rack so devices do not vanish from the grid in the middle of a task, and how to bring order to phone numbering.

What matters about connections

Lusiesta Studio works with phones over USB through ADB only: there is no Wi-Fi or local network connection in the app. That means any physical problem along the "phone - cable - hub - PC port" path is immediately visible in the dashboard: the tile goes offline, the preview goes dark, the task fails.

The app re-reads the device list every few seconds, so a reconnected phone returns to the grid on its own, without restarting the program. There is also a small grace window: a device that was alive a moment ago keeps showing as online for about 20 more seconds while it reconnects, so a single hiccup does not make the tile flicker.

Why a passive hub drops devices

A computer port supplies a limited current, and a passive hub (one without its own power adapter) simply splits that current across every socket. While the phones sit idle this may be enough. As soon as work starts - the screen lights up, video is encoded for the preview, an APK is installed, a scenario runs - consumption spikes, voltage sags, and the USB controller starts losing devices.

From the outside this looks like "buggy software": tiles go offline in batches, the stream breaks up, APK installation stops halfway. In reality the phones simply do not have enough power. Another telltale sign: the device appears to be "charging", yet the battery percentage slowly drops - which means the port delivers less than the phone draws under load.

How to estimate hub power

Do the math roughly and with headroom:

1. Budget around 1 A (about 5 W) per working phone - that is the current at which a device both works and does not discharge.
2. Multiply by the number of ports you will actually use: 10 phones means about 10 A, so a power adapter of roughly 50 W and up.
3. Add about thirty percent of headroom: adapters rarely deliver their rated output for long, especially in a warm room.
4. Look not only at total power but also at how much the hub delivers per port. Cheap models cap a port at 0.5 A, and a phone under load will discharge no matter how many watts are printed on the adapter.

The clearest sign that you picked the wrong hub: the farm sits perfectly still when idle, but the moment you start tasks on every device at once, several phones drop off together. One problem device is a device problem. Five at once is a power problem.

How to assemble the rack

• Buy hubs with external power (with a separate adapter), not passive ones.
• Do not daisy-chain hub into hub. Several hubs plugged into different computer ports beat one hub hanging off another: the shorter the path to the PC, the more stable it is.
• Spread the load across different PC ports. Connectors on the back panel of a desktop are usually more reliable than the front ones.
• Use short cables with proper data lines. There is a separate article on choosing them: USB cables: why you should not cut corners.
• Mount the phones on a shelf or in a rack with their screens facing you: that way you can see what is going on live and you do not step on cables.
• Do not pack the devices into a tight stack. They heat up under load, and overheating hurts both speed and connection stability.
• Label the hub ports and the phone bodies. Five minutes with stickers saves hours when you are tracking down a problem.

Device numbering

A phone keeps the same number everywhere in the app: "#1" in the grid, "#1" when picking devices for publishing, in warmup and on the "Proxies" page is one and the same device. The order is deterministic: the number is taken from the device map first (the devices_map.json file in the app data folder), and if the phone is not in the map, the number is assigned by its position in a stable order by serial number.

The practical takeaway: stick the number the phone shows in the dashboard onto its body. Then "number three failed" on screen and "number three" on the shelf are the same device, and you never have to compare serials by eye. The serial, by the way, is always visible in the card header and in list mode (the view toggle next to the grid) - in the list phones are rows with the columns "Device", "Profile", "Group", "Connection" and "Actions", and on a large farm finding a specific device there is easier than in tiles.

What happens to previews on a large farm

Live video is the heaviest part of the job. The app decodes only what is actually visible on screen and keeps a cap on simultaneously live streams (around two dozen). The remaining tiles wait for a slot and show their last frame, while invisible ones stop completely, freeing up the PC decoder, the phone encoder and the USB bus.

If the computer is struggling, reduce the load in "Settings", the "Interface" tab, the "Grid" section: set "Image quality" to "Economy", make the tiles smaller and turn on "Sleep mode" so the stream goes dark while idle. Tasks keep running meanwhile: warmup and uploading do not need a video stream - the picture is for you, not for the automation.

Keep the second limit in mind too - the one set by your plan. Phones above the plan limit are hidden in the grid behind a single tile that mentions hidden devices, and they do not start tasks. How this is counted is described in Plans and the device limit.

Testing the assembled farm

1. Connect all the phones and wait until the grid stops changing. The number of tiles should match the number of devices on the shelf.
2. Make sure no tile is stuck on "Offline" or frozen on the "Loading preview" message.
3. Apply load: start warmup or an APK installation on the whole farm at once and watch it for 10-15 minutes.
4. Keep the "Logs" page open: it shows which device dropped off and at what moment.
5. If the same group of ports always drops, the cause is the hub or its power supply, not the phones.

If devices still drop off

Replace one link at a time, going from cheap to expensive: cable first, then port, then hub. If the problem stays on exactly one phone after all the swaps, that phone is the issue - its connector, firmware or debugging settings. Common causes are collected in Device does not connect or is not visible.

One last word on scale: the farm stays manageable from a single window even at dozens of devices, a dropped phone is instantly visible by its tile and returns to the grid after reconnecting. All that is required from you physically is power, cables and hubs that hold up under load.