On a full server, players who spend more than about 8 minutes in the server login queue almost always fail to join. When their turn comes the server admits them, sends the world state and starts the preload camera. Then it receives no packets from the client for about 10 seconds and drops them with kick reason 4, "Connection with host has been lost." The player then has to re-queue, usually ends up waiting more than 8 minutes again, and fails again.
Players who wait under 8 minutes join normally, 682 of 684 today (99.7%). From 8 minutes the success rate falls to 39%, then to about 10%, and past 15 minutes it is close to 0.
The cut-off is sharp and sits at the same point across five separate server sessions. That points to a fixed timeout somewhere in the queue path (client, Steam networking or BattlEye), not to player network problems.