Why EarHorn Does Not Connect Over Bluetooth Unless You Ask

We spent a week at my aunt and uncle’s house, and every night went the same way. Put my daughter down. Start EarHorn on the phone by the crib, check it on mine, watch the meter twitch. Go downstairs and be an adult for a couple of hours.

Roughly ninety seconds after I sat down, the connection dropped.

Then I would restart it from the sofa, it would reconnect, and it would run perfectly for the rest of the night. Every night, same order, same delay. I spent that holiday reading logs.

What the phones were doing

Apple gives you a way for two devices to talk with no router at all: Bluetooth to find the other device, then a direct Wi-Fi link between the two. It is the reason AirDrop works on a train.

It is also, when both phones are in your hands at the crib, the fastest thing on offer. So that is what they picked. Neither phone was wrong. They were four inches apart, the direct radio was the obvious road, and they took it.

Then I close a door, and then carried one of them down a flight of stairs and through two walls, which that radio does not do. The house Wi-Fi was there the whole time, reaching both floors, being ignored.

The restart fixed it because by then the phones were far apart, the direct link was no longer on offer, and they settled for the boring one. The boring one was right all along.

The fix is a preference, not a ban

EarHorn now asks for the house Wi-Fi first when the house Wi-Fi is there. It does not forbid the direct link, partly because it cannot (that link reports itself as Wi-Fi anyway) and mostly because it should not: a household with no usable router needs it, and it is what works on a network that will not let two devices see each other.

So it stays, as a fallback. The setting that hunts for it ships off, and the screen that turns it on names the cost, which is battery: holding that radio up keeps a Wi-Fi chip from ever settling down to sleep.

One exception. Pairing raises the direct radio whatever the setting says, because two phones standing next to each other may have no network in common yet, and refusing to pair people in that situation would be a strange hill to die on.

The eighth of August is the tidiest evidence, both sessions in the log one after the other. The direct one lasted twenty-two minutes. The one I started from the sofa afterwards, over the house Wi-Fi, ran thirteen hours and eleven minutes and ended because somebody turned it off.

I still think about that week of restarts.

While I have you

I meant to ship this in July. Then I meant to ship it in August. It is September.

This post is roughly what the delay looks like. A bug that does not happen at home, so I cannot find it at home, and that turns out to be two phones making an entirely reasonable decision four inches apart. There have been several of those. Each one small, each one obvious in hindsight, each one costing a week of nights before it would show itself at all.

It is going out when the really dumb ones stop turning up. Thanks for waiting.

EarHorn is a convenience tool for audio monitoring and is not a substitute for attentive supervision.