problem is then you still rely on the module to switch lights on/off, when the device fails I don't have manual intervention. don't really mind not knowing the on/off state, just that if I say on or off change the state of the relay.
Wonder if there is any way to get the code and just change some lines
no, connected as per attached picture, basically the switches are in series but both with a NO/NC contact, so each switch can switch the light on or off, my one switch is the physical switch in the wall and the other one is the sonoff with the NO/NC contacts connected to the physical switch and the common to the light
Hence I'd like to use a phrase like : Alexa toggle kichen lights to change the state of the relay (since I might have switched the light on or off with the wall switch) or just say Alexa kitchen lights on (then the relay will change state to give the desired output - relay on/off might not correspond with actual ligtht on/off)
This has been extensively discussed in other threads here. I suggested they make a 3way switch that includes a current sensor. The presence of current load would indicate the light was burning.
Just for the record. What you are calling a 2-way switch is known to electricians as a 3-way switch. It has three connections. In order to operate a light with two switches you need two 3-way switches. In order to operate a light with three switches you need two 3-way switches and a 4-way switch.
What I would like to see produced is a 3-way wifi touch switch. All that is needed is to use a relay with Common, NC, and NO contacts. Incorporate a current sensor that will let the app know if the light is burning. With this one simple device a user could replace one of the 3-way switches in either of the diagrams above and operate the light via wi-fi. At the same time the other manual switches could also continue to work normally.
I agree EB but a nice 3-way switch would still be an excellent and easy product for ITEAD to manufacture. It would allow only replacing one switch instead of all of them and work seamlessly with manual switches.
The part about "can talk to each other" doesn't have a good track record. :-) Right now ITFFF and ewelink aren't talking which is a pain. That sort of thing doesn't inspire confidence!