Farmero runs each phone on its own USB tunnel, so adding phones is mostly a matter of plugging them in. The thing that breaks at scale is not the software — it is power, and it fails in a way that looks like a bug.
Power is the first thing to get right
A Mac's own ports can keep one or two phones charged while they work. Past that, the phones draw more than the ports can give, the voltage sags, and a phone browns out and drops off USB mid-run — which reads exactly like a flaky cable or a stuck runner. It is the single most common cause of trouble on a rack, and no amount of software can fix a phone that lost power.
So before the third phone:
- Use a powered USB hub — one with its own power adapter, not a small unpowered one that splits the Mac's power thinner. The adapter is the whole point; an unpowered hub makes the problem worse.
- Give the hub enough headroom. A phone that is both charging and being driven draws more than an idle one, and all of yours are working at once.
Cables matter more than they should
Every phone charges and transfers its clips over the same cable, so a cable that is fine for charging can still be too slow or too noisy for a run.
- Short and certified. MFi-certified data cables under a metre. Long or cheap cables are where "the phone disappeared mid-run" usually comes from.
- Data cables, not charge-only. Some cables carry power but no data; those never show the phone to the Mac at all.
What Farmero does and does not need
Farmero talks to each phone over the USB tunnel go-ios sets up, so the limits at scale are your Mac's USB bandwidth and power, not Farmero. It does not need the phones on Wi-Fi, it does not need them signed into iCloud together, and it does not care what order they are plugged in.
One more thing that is not hardware: keep every phone from sleeping (auto-lock off — see Connect an iPhone). A phone that locks itself is a phone that stops, and on a rack of ten that is one quiet failure an hour.
None of this is exotic. A powered hub and a handful of short certified cables is the whole shopping list, and it is the difference between a rack that runs all day and one that drops a phone every few hours for reasons that look like software and are not.