Unless you are experiencing other connection issues, the occasional "Lost connection with Domino server" and "Reconnected to Domino server" is nothing to worry about.
These messages occur because Domino occasionally checks the websocket connection status. If the connection is lost/disconnected, then a "Lost connection to Domino server" message will appear. The system will then attempt to reconnect. When the reconnect request succeeds a "Reconnected to Domino Server" toast message is displayed. This is normal behavior.
Below is an example of such error messages: