Summary: I have an existing set of the 401s running. In order to add these 406s I first had to break the 401 link, and in essence use the 406 as the "master".
Pros: I have a detached workshop made of steel and WIFI doesn't get through very well... this solved the issue out of the box... zero setup... just plug and play. I was happ...
Cons: Both the transmitter and the receiver flash red a good percentage of the time, which is sort-of annoying given that everything works fine even when the PL led is flash...