As reported in #5193, when the local client finished the loading screen but some other client didn't, there is the "Waiting for other clients" screen.
If said other client is actually losing the connection, it will not be seen onscreen and the waiting players are mislead to believe that the dropper is still loading.
This patch informs the host that there is likely a connection issue and that the client may be considered to be kicked rather than waiting a minute or longer while players lose patience.
This will be especially important after D1513.