Chess.com so laggy

I seriously don't know why chess.com so laggy these day
When I was playing chess (on a crazyhouse tournament), it just kept disconnected. I have tried to reload the page but it kept disconnecting. When I went to to check the speed of my Internet, it said 400 Mbps (which is very fast btw). I have tried to restart my computer but when I play another game, it just disconnected. I am very mad about that because Lichess done it better, I played 15 second on it and it was smoothed and had no Internet delay, I pl
So what should I do now to not being disconnected although my Internet connection is very good? Or it is because chess.com is very laggy so that I will change to play on Lichess