I am looking for a smart solution to add dimming capabilities to our foyer lights that can be controlled by 3 on-off switches. Here are how they are wired, based on (somewhat extensive) tinkering with a multimeter. Overall, there seems to be a first switch that takes the live wire, and then traveler wires are used to transfer that live (based on switch position) to the downstream switches. I am almost certain that I have the neutral wire after the bulbs available in the gangbox of that last switch.
I prefer a smart dimmer relay over a switch because this way, I get to keep the existing look of the switch (I don’t care much for the “dimmer” functionality on the switch itself, but on/off should work). If I do have to go with a switch, I would ideally just try to replace the middle switch because it’s the only switch in its box, and then it can look a little different I guess.
So, what are my options? So far, I have tinkered in trying to get a Shelly Dimmer 2 working but with no luck. For additional reference info on my smart home - I am in the US, I use Home Assistant and have both Z-wave and Zigbee environments running.
A little more info now I’ve fully read your post: You have several options. If you have a permanent L and N at the light, you can just fit one Shelly there, and use the switch wire as a trigger.
If you only have a N at the light, and you only have an L at the first switch, you’ll need 4x Shelly’s. You’d join the L all the way to the lamp, and join the N all the way to the first switch. Then you’d have a permanent supply at each switch plus the light. Fit a Shelly behind each switch, and connect the switch to it’s inputs. Fit a Shelly at the light, and connect the light to it’s output.
Then you need to connect all Shellys together via wifi. You can either do this directly (device to device) or you can do it via the home wifi.
The function of each switch could be individually controlled, and the light can be switched on/off via app, timer, smart home system etc.