Server problem or mine?


The site allows a certain amount of lag that is forgiven
Some things you can do to minimize issues, though not all lag is solvable.
https://support.chess.com/en/articles/8584209-how-do-i-fix-my-disconnect-lag-issues
https://support.chess.com/en/articles/8652402-how-can-i-optimize-my-online-chess-performance