[Wiring Help] ZBMiniL2 (Extreme) -not working right- Stair case 2-switch

(I set up a ZBminiL2 just fine on a single switch situation. It works great)

But when I tried to do one in my stairway that has 2 switches (I set it up on the switch at the top of the stairs), I must be doing something wrong because the switch at the bottom SOMETIMES works, but not always. This makes me think I wired it wrong.

The switch it is connected to, had a black wire (Live wire?) & white wire (Load?) on the same side (just like the single switch had) and it also had a third red wire on the other side of the switch.

So I connected the ZBMiniL2 similarly to how I got the Single switch to work: White wire went into L out, Black wire went into L in, then I connected S1 to the Switch terminal that previously had the black wire, and S2 to the switch that previously had the white wire. I left the red wire in place. Basically like this:

When I first tested it, both switches worked, but within a day, I noticed glitches. The top switch always works, and the app can control the relay, but now sometimes the bottom switch works normally, but sometimes it doesn’t work (might partially depend on the position of the top switch and whether the relay changed the light on/off through the app). I must have it wired wrong. I can’t imagine Sonoff designed the relay to not let the bottom switch always work consistently. Can I get some recommendations of how to change my wiring if I did it wrong?

Yes I have seen the wiring diagrams that come with the instructions.

That’s what I tried to follow to do the wiring I currently have set up, but I must have misunderstood or misinterpreted them. Doing the wiring as I described above makes it work perfectly for my single switch situation, but it’s not working perfectly for the 2-switch setup. Was I supposed to use the red wire somehow instead?

Do I need to use a wire cap to split the Black wire (1 go to L in, and 1 go back to the terminal on the switch the black wire was already originally connected to?
Do I need to use a wire cap to split the White wire?

Basically, we have the following:

3 Wires originally:

  • Black (live?),
  • White (load?),
  • Red (to bottom Switch?).

3 terminals on the switch:

  • Black Terminal = where the black wire was originally connected on the right side
  • Green Terminal = where the white wire was originally connected on the right side.
  • Red Terminal = Where the red wire was connected on the left side

Then the ZBMiniL2 Terminals:

  • L out
  • L in
  • S1
  • S2

Can anyone describe for me, which color wire goes to which terminal, and which ones need a new wire?

I currently have the following:

  • White wire connected to L out
  • Black wire connected to L in
  • S1 Connected to Black Terminal
  • S2 connected to Green Terminal
  • Red Wire connected to Red Terminal, unchanged from where it originally started.

What should I do differently?

Thanks in advance for anyone who got this far or tries to help :pray:

The red wire in your (funny) drawing is connected to the switch terminal on one side with the other side connected to what?
The design of the boxes and switches and the colours of the wires suggest that you are from the USA or Canada, right?

I’m not sure. I would’ve assumed this would be standardized, but I am quickly learning that this may not be the case. I had thought that the red wire connects to the other switch (at the bottom of the stairs). I am not confident how to figure this out. The light itself is a really high chandelier in the middle of the ceiling over stairs. I don’t even think I could get a ladder up to the light to check the wiring at the light. There is nothing to prop a normal ladder up to near that spot.

Yeah USA. It’s a house that has lighting setup with a “no neutral” wiring configuration, which is why I got the Sonoff ZBMiniL2 which I’m told was designed to handle no neutral lighting.

It must be an older house then. Older hoses and apartments do not have neutral wires delivered to wall box. That used to be the standard for lighting. The same was in EU. But this is not the main problem.
You need to discover how many wires run between boxes. If there are only two, there’s no chance to utilise ZBMINI-L2 in your case. Read this thread.