My clock is stoping when i don´t have connection problems.

This sometimes happens when the connection between you and the server breaks. lichess.org/lag

Also brazilian here and I've had the same issue just these days.
Just wonder why specific connection breaks when other connections seem ok.
Previously, the game freeze would happen when the whole internet connection is lost, and the "reconnecting" notification would show up.

@lovlas It seems very strange to me that the connection on one device would break while the connection on another device does not, especially when those two devices are using the same internet connection through the same WLAN.

Refreshing the page (as has been suggested somewhere) seems to help.
With that in mind, it is only annoying, but not a game-breaking issue.