Can't connect to color bulb

Hello, I bought a yeelight color bulb about 2 weeks ago.
I had a lot of troubles to connect it but finally succeed, but 2 days later, it appeared offline and couldn’t get it back online so I tried to remove it and reconnect it and I couldn’t connect back to the bulb since…

How about changing DNS of your router to 8.8.8.8 and try again?

Hello, due to the model of my rooter, I cannot change my DNS…