So a solution here anyway, I moved all the Echo devices onto the guest network. While they are still able to find other home automation devices (Nest) on the main network, they do not interfere any longer with Naim.
Along the way, I learned that it is not only Naim devices that have issues with Echo, so do many AirPlay enabled devices.
Good call David.
Might give this a try. I am hopeful that Naim can provide a fix.
No issue with my Echo and home automation here with my Naim, Apple Airplay, Spotify, and Sonos Connect ... am intrigued to find what the issue is that some people are having.... looking at my network, everything seems to be well behaved, but then I use Cisco network equipment.
Would be interesting to see if the Beta software you are using provides a fix?
Bizarre that my Naim Muso's are not affected, just the NDS.