My bulb and lightstrip don’t answer in the Apple home app


First of all, sorry for my English. I’m from France.

I have a problem with my Yeelight LED Bulb and Lightstrip. I can add them to the Apple home app without any issue and then I can control them from there or my HomePod. But after a while, they don’t answer anymore… So I have to unplug and re-plug them for them to work. I tried to change my rooter settings but nothing seems to work. I don’t understand why it works perfectly at the beginning and then it doesn’t…

I hope you will be able to help me with this: I would be very grateful. I thank you in advance!