Resolved more code where we didn't need to define separate BAC_ROUTING functionality, since the npdu_encode_pdu() will do the right thing if our source address is for the gateway (root device), because src->net and/or src->len will be 0.

For the important Device_Object_Instance_Number(), will redirect to the Routed_Device_Object_Instance_Number() function if this is a routing build.
This leaves only the Who-Is and Who-Has handlers to be dealt with.

bacnet-stack/demo/handler/s_upt.c

@@ -53,22 +53,16 @@ void Send_UnconfirmedPrivateTransfer(
     int pdu_len = 0;
     int bytes_sent = 0;
     BACNET_NPDU_DATA npdu_data;
-#if BAC_ROUTING
     BACNET_ADDRESS my_address;
 
-    my_address = *Get_Routed_Device_Address(-1);
-#endif
-
     if (!dcc_communication_enabled())
         return;
 
+    datalink_get_my_address(&my_address);
     /* encode the NPDU portion of the packet */
     npdu_encode_npdu_data(&npdu_data, false, MESSAGE_PRIORITY_NORMAL);
-#if BAC_ROUTING
     pdu_len = npdu_encode_pdu(&Handler_Transmit_Buffer[0], dest, &my_address, &npdu_data);
-#else
-    pdu_len = npdu_encode_pdu(&Handler_Transmit_Buffer[0], dest, NULL, &npdu_data);
-#endif
+
     /* encode the APDU portion of the packet */
     len =
         uptransfer_encode_apdu(&Handler_Transmit_Buffer[pdu_len],