Why was the connection closed?
If a message appears on your chart that the connection was closed, then you have reached the limit of the allowed number of connections for your plan. One connection is considered one open page /chart.
If the limit is reached, the oldest open connection is closed and a window is shown in this tab with a message that the limit has been exceeded and the connection has been terminated.
In the window, you can see the number of connections that is available for each user plan.
If the limit has already been reached, then restoring the current connection will break the connection in another window/tab.
If you close the window with a cross, then you will remain on the chart with a disconnected connection and it will be possible to restore it only by refreshing the page.
Please note that you can optimize your connections using multi-chart layouts. Essential users can open 2 charts per one tab, Plus users can open up to 4 charts, and Premium users can open up to 8 charts per one tab. While our Professional plans provide even more space for advanced charting: 10 charts in one layout for Expert plans, 12 charts in one layout for Elite plans, and 16 charts in one layout for Ultimate plans. Here's more info on this feature: How to enable the multi-chart mode?