diff --git a/RP_L4/RPL4PB.cpp b/RP_L4/RPL4PB.cpp
index 86ae448..f275dc1 100644
--- a/RP_L4/RPL4PB.cpp
+++ b/RP_L4/RPL4PB.cpp
@@ -419,6 +419,47 @@ void
 	NetworkManager *net_mgr = GetNetworkManager();
 	Check(net_mgr);
 	NetworkClient *client = net_mgr->GetNetworkClientPointer(packet->clientID);
+
+	//
+	// Say what is being routed where, for the first few.
+	//
+	// Playback dies inside Mission::Mission, reached through the egg file
+	// handler, while dispatching spooled packets - so a packet is arriving
+	// at a client that is not the one it was recorded for. Client IDs and
+	// message IDs are both small integers counted from the same base
+	// (NetworkClient::NextMessageID is 3, so the interest manager's
+	// NewDynamicEntity and the network manager's ReceiveEggFile are BOTH
+	// message 3), which makes a mis-routed packet look perfectly valid to
+	// whoever receives it. Naming the pair and the client it resolved to
+	// ends the guessing.
+	//
+	// A NULL client is the other candidate: Check() is a no-op in a
+	// release build, so a missing interest manager would be a call through
+	// nothing rather than a complaint.
+	//
+	{
+		static int said = 0;
+
+		if (said < 24)
+		{
+			++said;
+			DEBUG_STREAM << "Playback: packet client=" << (int) packet->clientID
+				<< " message=" << (int) packet->messageData.messageID
+				<< " length=" << (int) packet->messageData.messageLength
+				<< " -> client " << (void *) client
+				<< (client == NULL ? " (NULL!)" : "")
+				<< (client == (NetworkClient *) net_mgr ? " = the NETWORK MANAGER" : "")
+				<< (client == (NetworkClient *) this ? " = the application" : "")
+				<< (client == (NetworkClient *) GetInterestManager()
+						? " = the interest manager" : "")
+				<< "\n" << std::flush;
+		}
+	}
+
+	if (client == NULL)
+	{
+		return;
+	}
 	Check(client);
 	client->ReceiveNetworkPacket(packet, &packet->messageData);
 	Check_Fpu();