Network Error force loads Entry map for client when server shuts down

found.

void UEngine::HandleDisconnect( UWorld *InWorld, UNetDriver *NetDriver )
{
	// There must be some context for this disconnect
	check(InWorld || NetDriver);

	// InWorld might be null. It might also not map to any valid world context (for example, a pending net game disconnect)
	// If there is a context for this world, setup client travel.
	if (FWorldContext* WorldContext = GetWorldContextFromWorld(InWorld))
	{
		// Remove ?Listen parameter, if it exists
		WorldContext->LastURL.RemoveOption( TEXT("Listen") );
		WorldContext->LastURL.RemoveOption( TEXT("LAN") );

		// Net driver destruction will occur during LoadMap (prevents GetNetMode from changing output for the remainder of the frame)
		// The ?closed option will also make sure any PendingNetGame is cancelled in Browse
		SetClientTravel( InWorld, TEXT("?closed"), TRAVEL_Absolute );
	}
	else if (NetDriver)
	{
		// If the NetDriver that failed was a pending netgame driver, cancel the PendingNetGame
		CancelPending(NetDriver);

		// Shut down any existing game connections
		if (InWorld)
		{
			// Call this to remove the NetDriver from the world context's ActiveNetDriver list
			DestroyNamedNetDriver(InWorld, NetDriver->NetDriverName);
		}
		else
		{
			NetDriver->Shutdown();
			NetDriver->LowLevelDestroy();

			// In this case, the world is null and something went wrong, so we should travel back to the default world so that we
			// can get back to a good state.
			for (FWorldContext& PotentialWorldContext : WorldList)
			{
				if (PotentialWorldContext.WorldType == EWorldType::Game)
				{
					FURL DefaultURL;
					DefaultURL.LoadURLConfig(TEXT("DefaultPlayer"), GGameIni);
					const UGameMapsSettings* GameMapsSettings = GetDefault<UGameMapsSettings>();
					if (GameMapsSettings)
					{
						PotentialWorldContext.TravelURL = FURL(&DefaultURL, *(GameMapsSettings->GetGameDefaultMap() + GameMapsSettings->LocalMapOptions), TRAVEL_Partial).ToString();
						PotentialWorldContext.TravelType = TRAVEL_Partial;
					}
				}
			}
		}
	}
}

You need to change this function has you need.
Mostly this line
PotentialWorldContext.TravelURL = FURL(&DefaultURL, *(GameMapsSettings->GetGameDefaultMap() + GameMapsSettings->LocalMapOptions), TRAVEL_Partial).ToString();

Require to build yourself the engine by the way.