My previous post on this problem has disappeared, so this is a repost in response to yves_b from the TP-Link Community Team.

In my  ome system, I replaced an ASUS router with the 3-unit deco and the replacement went very successfully with 10 clients.  I have a radio unit which has an ethernet port and an internal web interface for control.  That radio is connected into the LAN through an ethernet hub and into an ethernet port on the main Deco unit.  I am able to see the radio as a client in the network and can PING it from a PC.  The radio is set to send data via UDP to a Windows 10 PC which is connected to the same Deco unit via WIFI.  Both the radio and the PC have address reservation.  The radio setup specifies the two ports and IP addresses for the ends of the UDP.  There is software in the PC which receives the UDP and also specifies those ports and IP addresses.  I have double checked the port/IP setup. 

I am able to ping the radio from the PC and can access it's web interface.  The ohly problem is that the UDP never starts.  This was all previously working on the ASUS router.  I saw a post in the community about port forwarding, but it indicates that is for opening external ports.  Since everything is internal to the Deco LAN, I did not do that.  Am I interpreting this wrong?

Thanks for any help,

Paul