I have the same problem. Yeelight ceiling lights just disconnected easily and they could not be connected to network again without switch off/on the power circuit or reset the lamp. But then the lights will go offline again. I have been using this product for a few months. It works okay in the past. Also other xiaomi switches/ desk lamp works fine and connect well to the network. Please assist.
I had these problems in the past and it turned out to be a router problem. After I bought new more powerful router, I never had this issue again. Before, if I turned off the light, I had to turn off the router and light in order to connect. Seems the router had the problem connecting all devices if there were many devices (cca >20) connected.