Shelly switch modes: which input mode suits the switch on your wall

A Shelly relay does not work out for itself what kind of switch you have wired to it. You tell it, in two settings that sit next to each other on one page of the device's own web interface. Get either one wrong and the light still works, just not the way you expect. That is why so many Shelly problems look electrical and are not.

The two settings you are choosing between

Select input mode answers a question about hardware: what is physically wired to the switch terminal. Two of its answers matter for a wall switch, and Shelly describes them like this.

• Button: "every button press toggles the state of the device output."
• Switch: "the position of the switch corresponds to the state of the device output."

There is a third option, Analog, which the guides note is "not present as an option in all devices". It reads a brightness percentage rather than a wall switch, so it is not part of this question.

Set output type answers a different question: what the relay should do about that input. There are four, and the bracketed qualifiers below are Shelly's own.

Those qualifiers do real work. You cannot select Momentary on a Switch input, and you cannot select Toggle or Edge on a Button input. So several of the wrong combinations people describe on forums were never selectable, which tells you the setting that is actually wrong is usually the input mode rather than the output type.

Match the mode to the switch on your wall

A rocker

The standard Australian wall switch stays where you put it, which is exactly what Switch mode describes. Set the input mode to Switch and the output type to Toggle, and the relay follows the plate: down is on, up is off, and the switch on the wall always tells you the truth about the light. This is the default worth reaching for on a normal light circuit.

A push button

A push button springs back the moment you let go, so it has no position to report. It wants Button input and a Momentary output type, where each press toggles the light and the button's resting state means nothing. Retrofits and bell presses are the usual reason to be here, and it is the one case where the wall hardware genuinely cannot tell you whether the light is on.

A two-way pair

Two plates control one light from opposite ends of a room, and they share a single input on the relay. Shelly covers this directly, though not under the name you would search for: its installation guides call it running a light from multiple switches, and they set the input mode to Switch and the switch mode to Follow, which is this device's Toggle. Do that and either plate changes the light. Edge behaves the same way on a pair, so it is not a mistake, but Toggle is the setting the manufacturer names. What neither mode can give you is a fixed on position, because two plates share one input: whether the light is on depends on whether the two plates agree, so one end will always read backwards. Getting the loop itself onto the relay is a wiring question rather than a mode question, and the terminal-by-terminal diagrams cover it.

A switch you keep only for automations

Detached is the odd one out, because it is the mode where the switch stops controlling the light on purpose. Shelly puts it plainly: "you won't be able to control your light through the input." People choose it when the light itself is smart and should stay powered, so the relay holds the circuit on and the wall switch becomes a trigger for Home Assistant or the Shelly app instead. It is also the answer that surprises people most, because a light that no longer responds to its switch reads as a fault. Worth knowing before you commit to it: if the thing listening to that input stops listening, the switch does nothing at all, which is one more reason to understand what a Shelly can still do on its own.

The mismatches, and what each one looks like

Each wrong pairing fails in its own recognisable way, which means the symptom tells you which setting to change. Find the row that matches what your light is doing.

One caveat on those two-way rows. Shelly's web interface guides, which is where the mode descriptions live, say nothing about wiring a light to more than one switch. Its installation guides do, under the heading of multiple switches rather than two-way, and that is where the Switch and Follow settings above come from. Those guides show their wiring in a diagram rather than describing it, so they do not state whether they mean a changeover pair or two switches wired in parallel. Where we have gone past what they write, we say so.

Three more settings that cause the same complaints

A mode that reads correctly can still be undone by a setting further down the same page. These three are the usual culprits, and none of them appears in the mode list.

Invert

This one reverses the logic of the input signal. Shelly's description is worth quoting because it names the symptom directly: "when the input signal is ON, the device will turn OFF, and when the input signal is OFF, the device will turn ON." So a rocker set correctly to Switch and Toggle, but running upside down after an install, is often an Invert question rather than a mode question. It is the fastest fix for a plate that works perfectly and is simply the wrong way up.

Action on power on

This decides what the relay does when the power comes back after an outage. Turn ON and Turn OFF do what they say. "Restore last known state" puts the output back where it was before the power went. The fourth, "Current state of the switch", is offered on Toggle Switch only and reads the plate on the wall, which is the option you want if the wall switch is meant to be the source of truth. Leave it on the wrong one and you get a light that comes on by itself after a blackout, which people quite reasonably report as a mode fault.

Lock inputs

The bluntest of the three. Shelly describes it as ignoring "all changes to physical inputs, regardless of the mode they are in". Switched on by accident, it looks exactly like Detached, and no amount of changing the output type will bring the switch back. Check it before you go any further with the mode settings.

The names change depending on where you look

One reason this is hard to search is that Shelly's own documentation uses more than one name for the same setting, and which name you see depends on how old the device is. On Gen3, Gen4 and Pro relays the two settings are "Select input mode" and "Set output type", and the guide for the i4 notes that the first "can also be titled Switch mode for some devices", which is the phrasing most people actually type into a search box. Search results written against a different generation will not match what is in front of you.

The original Shelly 1, 1L, 1PM, 2.5 and Dimmer 2 work differently again. Instead of two settings they give you a single list, called "Set relay type" in the web interface and "Button Type" in the app, with five entries rather than four: Momentary, Toggle switch, Edge Switch, Detached Switch and Activation Switch. That fifth one has no equivalent on the newer relays. Shelly describes it as being for use with a motion sensor, where any input turns the output on and resets the auto-off timer. On these devices Invert is called "Reverse inputs", and there is a separate Long Push time you can set in milliseconds. If an answer you have found does not match your screen, check which generation you are holding before you change anything.

None of this changes which relay you need, only how you set it up once it is in. If you are still choosing, the picker walks you to the right model.