“The app recognises the Shelly BLU Wall Switch 4, but when it asks me to press a button on the device it cannot find it. I have reset it several times and nothing.” We get this one often, and it usually has a simple fix: the fault is rarely in the unit.
How pairing works, and why that matters
The BLU Wall Switch 4 is a Bluetooth remote running on a CR2032 cell, with no mains supply. That has one direct consequence: the unit only speaks for a second when you press a button, and only if the battery has charge in it.
When the app says “press a button on the device”, that transmission is exactly what it is waiting for. If it does not arrive, the app will not confirm — even though it listed the remote a moment earlier from its Bluetooth advertisement, which costs far less power.
The three causes, in order of likelihood
1. The battery
By a wide margin the most common. It ships with a CR2032 fitted, but that may still have a plastic tab in place, or have gone flat after months in a warehouse.
What throws people: a marginal cell is sometimes enough for the unit to advertise but not to transmit on a press. Hence a remote that appears in the list and fails at the very next step.
2. The reset never happened
A factory reset only works immediately after inserting the battery. If you held the button down without first removing and refitting the cell, the reset did not run — however many times you tried. That is the whole story behind “I have reset it several times and nothing”.
3. Range and permissions
While pairing, the phone has to be within a metre, with Bluetooth on and location permission granted to the Shelly app. Android needs location access to scan over Bluetooth at all, and without it nothing is found.
How to add it, in this order
The first two steps settle it almost every time.
- Fresh battery. A branded CR2032, + side up, seated properly. Do not rule out one straight from the blister: if the remote sat in storage, it may arrive low.
- A real reset. Take the cell out, put it back, and within 30 seconds hold a button for 30 seconds. That is the reset that actually clears previous pairings.
- Pair up close. Phone within a metre, Bluetooth and location on, add a Bluetooth device, and press a button when asked. If it does not appear, press any button four times to open the pairing window — it lasts a minute — and try again.
- Gateway ready. Have the BLU Gateway, or another Shelly acting as a Bluetooth gateway, plugged in and online so the remote becomes usable and keeps its settings.
The gateway: what can bridge and what cannot
This is where most people get stuck. The remote needs a permanently powered Bluetooth gateway to work with the app, with scenes, and from away. And not every Shelly will do: a Gen1 unit has wifi only, so it cannot bridge Bluetooth — there is no Bluetooth radio in it to listen with.
The BLU Gateway works, and so does any mains-powered Shelly with wifi and Bluetooth that is not a sensor, with the gateway function enabled.
If the remote pairs fine but the buttons do nothing, this is not your problem: the action lives in a scene rather than on the button. That has an article of its own.