Fake kids. After 2 months of operation, it starts having problems with wifi connection and after 1 month it breaks down completely

The extender is to blame, it's just a battery eater. It works well sometimes, but it doesn't always send a disconnection notification. I don't know if it's because it's playing through the extender, but it shouldn't. It sends a notification when the door is closed and when it's opened though

Attention, it only sends a signal when opening and not when closing, so for example, you only know if someone opened the door and not if they closed it.

Other than that, it works fine.

I bought 5 contacts. 2 of them worked fine. The other 3, for some reason, drained the batteries in seconds and you could tell because the batteries were overheating. At first, I thought it was the batteries, but I bought new ones, tested them, put them on, and the 3 contacts still didn't work. They just drained the batteries. Possibly faulty pieces?
I want to emphasize that the RF version only has one state, it simply sends a signal that the contact has opened to an RF bridge, unlike the wifi version which is standalone and has an open/close state where you can work with it better in scenarios.

It does what it says. It is a Single State Sensor, which means it simply sends a signal when the door opens only. Together with Sonoff's RF Bridge, I have installed them in HomeAssistant and all automations work perfectly.