How to wire Shelly 2.5 in circuit with 3 switches?

    I am having some trouble wiring my Shelly 2.5 to toggle a light so that is controlled by three switches while also having home assistant control.

    See this diagram I made

    There are three electrical boxes. All of the electrical boxes have black hot wires for other lights that are not drawn in my diagram in the event that those are helpful.

    Electrical Box 1

    Power from breaker

    3-way switch

    Electrical Box 2

    4-way switch

    Electrical Box 3

    3-way dimmer switch

    output wire connected to light

    What is the correct way to wire this so that all the switches work in tandem with home assistant? I have the Shelly relay set to Power On Default: Restore last mode and Button Type: Edge Switch

    I tried putting the Shelly in electrical box 3 using the black wire on the dimmer switch going to SW1 and the output connected to the light. When its connected this way the light switches either work normally or flicker. See this table for the switch behavior if provides any insight.

    Welcome to the forum!

    Main issues are:

    (a) The combined Dimmer/3-way switch, and

    (b) A total lack of wires in your setup.

    Could you imagine to replace the switches with buttons? In this case a Shelly Dimmer2 could be used for dimming:

    [Blockierte Grafik: https://smarthome-forum.eu/index.php?media/494-ar768-tasterschaltung-png/]

    The red wire in your installation would work as the „button wire“ and has to be connected to pin SW of Shelly Dimmer2. The other pole of all three buttons are connected to live wire (white). Thus, the three buttons are connected in parallel.

    „Habt Geduld. Alle Dinge sind schwierig, bevor sie einfach werden!“ (aus Frankreich)

    „Nothing in life is to be feared, it is only to be understood.“ (Marie Curie, 1867-1934)

    „Es reicht nicht“, rief Schiller, „Gedankenfreiheit zu fordern, man muß auch denken können, sonst fordert man Gedankenlosigkeitsfreiheit und die ist die Freiheit zur Dummheit, welche wiederum die schlimmste Unfreiheit überhaupt ist!“
    (Aus „Besuch aus Weimar“ von Gert Heidenreich, Schriftsteller, *1944 in Eberswalde)

    To your questions:

    (a) To operate a Shelly at the leftmost box (where the dimmer/switch is located), you would need a live wire - which isn’t there! And no spare wires are available to amend this situation.

    (b) Controlling a Shelly’s SW input with a combined dimmer/switch isn’t possible. The dimmer looses its function and the input will be permanently activated due to the internal electronics in the dimmer/switch.

    At last, you’ve added a complete view of the leftmost box. Thanks - this would have helped if known from the beginning! Obviously, there is live potential available. Hence, you may replace the dimmer/switch by a normal three way switch and use this diagram:

    [Blockierte Grafik: https://smarthome-forum.eu/index.php?media/199-ar768-kreuzschaltung-png/]

    „Habt Geduld. Alle Dinge sind schwierig, bevor sie einfach werden!“ (aus Frankreich)

    „Nothing in life is to be feared, it is only to be understood.“ (Marie Curie, 1867-1934)

    „Es reicht nicht“, rief Schiller, „Gedankenfreiheit zu fordern, man muß auch denken können, sonst fordert man Gedankenlosigkeitsfreiheit und die ist die Freiheit zur Dummheit, welche wiederum die schlimmste Unfreiheit überhaupt ist!“
    (Aus „Besuch aus Weimar“ von Gert Heidenreich, Schriftsteller, *1944 in Eberswalde)