Joe,
When I join a match with that host running it crashes when a party member joins the match and reconnects to the party leader. The crash occurs when the NetDriver is replicating relevant actors (I assume other beacons?) because its expecting a GameMode in the NetDriver. Am I missing something in the NetDriver or Connection?
The beacon is also based on an actor which is removed between levels so I imagine I need to recreate and reconnect every time the party joins or leaves a server, yes?
edit:
Specifically these lines cause the crash.
AGameMode const* const GameMode = World->GetAuthGameMode();
bool bLowNetBandwidth = !bCPUSaturated && (Connection->CurrentNetSpeed / float(GameMode->NumPlayers + GameMode->NumBots) < 500.f );