Hi,

i have a issue with a sonoff Dual R3 thats randomly turning on and off.

Sometimes its just turning on or off and other times its really fast switching on off like a few times a second.

I already tried 3 brand new ones but all have the same issue but are working fine on other circuits.

They are mounted in the main distribution board and the switching cables are about 12m long. Some even longer cables which are running parallel to the problematic ones are working fine.

I am thinking its some sort of emi on the cables. They are plane unshielded electrical wires. I already tried some pull down resistors on the s1 / s2 ports but it didnt help.
I also dont understand how the device is detecting a switch on the line as the s1 port measured to neutral shows 230V (switch turned off) and when the switch is turned on it just connects L1 to S1 so i dont understand how it should know that there has been a switch.